diff --git a/CMakeLists.txt b/CMakeLists.txt
index f81a308..5254573 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -48,6 +48,7 @@ add_library(fesa_core STATIC
     src/fesa/results/result_database.cpp
     src/fesa/solvers/linear/pardiso_linear_solver.cpp
     src/fesa/validation/comparison.cpp
+    src/fesa/validation/reference_csv.cpp
 )
 
 target_include_directories(fesa_core
diff --git a/include/fesa/validation/reference_csv.hpp b/include/fesa/validation/reference_csv.hpp
new file mode 100644
index 0000000..2903eb2
--- /dev/null
+++ b/include/fesa/validation/reference_csv.hpp
@@ -0,0 +1,28 @@
+#pragma once
+
+#include <filesystem>
+#include <string_view>
+#include <vector>
+
+#include <fesa/core/diagnostic.hpp>
+#include <fesa/validation/comparison.hpp>
+
+namespace fesa {
+
+struct ReferenceRow final {
+    ReferenceQuantity quantity;
+    ResultPosition position;
+    std::vector<double> values;
+};
+
+struct ReferenceCsvReadResult final {
+    std::vector<ReferenceRow> rows;
+    std::vector<Diagnostic> diagnostics;
+};
+
+[[nodiscard]] ReferenceCsvReadResult read_reference_csv(
+    ReferenceQuantity quantity,
+    const std::filesystem::path& path,
+    std::string_view single_instance_name);
+
+}  // namespace fesa
diff --git a/src/fesa/validation/reference_csv.cpp b/src/fesa/validation/reference_csv.cpp
new file mode 100644
index 0000000..a17e0ae
--- /dev/null
+++ b/src/fesa/validation/reference_csv.cpp
@@ -0,0 +1,446 @@
+#include <fesa/validation/reference_csv.hpp>
+
+#include <algorithm>
+#include <array>
+#include <charconv>
+#include <cmath>
+#include <cstddef>
+#include <cstdint>
+#include <fstream>
+#include <iterator>
+#include <map>
+#include <optional>
+#include <set>
+#include <sstream>
+#include <string>
+#include <string_view>
+#include <tuple>
+#include <utility>
+#include <vector>
+
+namespace fesa {
+namespace {
+
+constexpr std::string_view instance_column{"Part Instance Name"};
+constexpr std::string_view node_column{"Node Label"};
+constexpr std::string_view element_column{"Element Label"};
+
+using PositionKey =
+    std::tuple<std::string, std::int64_t, std::optional<std::int64_t>>;
+using ColumnIndices =
+    std::map<std::string, std::size_t, std::less<>>;
+
+std::size_t column_index(
+    const ColumnIndices& column_indices,
+    const std::string_view name) {
+    return column_indices.find(name)->second;
+}
+
+std::string_view trim(const std::string_view value) {
+    constexpr std::string_view whitespace{" \t\f\v\r\n"};
+    const std::size_t first = value.find_first_not_of(whitespace);
+    if (first == std::string_view::npos) {
+        return {};
+    }
+    const std::size_t last = value.find_last_not_of(whitespace);
+    return value.substr(first, last - first + 1U);
+}
+
+std::vector<std::string> split_fields(const std::string_view line) {
+    std::vector<std::string> fields;
+    std::size_t first = 0U;
+    while (true) {
+        const std::size_t comma = line.find(',', first);
+        const std::string_view field =
+            comma == std::string_view::npos
+                ? line.substr(first)
+                : line.substr(first, comma - first);
+        fields.emplace_back(trim(field));
+        if (comma == std::string_view::npos) {
+            break;
+        }
+        first = comma + 1U;
+    }
+    return fields;
+}
+
+ReferenceCsvReadResult failure(
+    const DiagnosticStage stage,
+    std::string code,
+    std::string message,
+    const std::filesystem::path& path,
+    const std::size_t line) {
+    std::vector<Diagnostic> diagnostics;
+    diagnostics.push_back({
+        stage,
+        Severity::error,
+        std::move(code),
+        std::move(message),
+        SourceLocation{path, line, line == 0U ? 0U : 1U},
+    });
+    return {{}, std::move(diagnostics)};
+}
+
+ReferenceCsvReadResult validation_failure(
+    std::string code,
+    std::string message,
+    const std::filesystem::path& path,
+    const std::size_t line) {
+    return failure(
+        DiagnosticStage::validation,
+        std::move(code),
+        std::move(message),
+        path,
+        line);
+}
+
+bool is_valid_utf8(const std::string_view text) {
+    std::size_t index = 0U;
+    while (index < text.size()) {
+        const auto first = static_cast<unsigned char>(text[index]);
+        if (first <= 0x7FU) {
+            ++index;
+            continue;
+        }
+
+        std::size_t continuation_count = 0U;
+        std::uint32_t code_point = 0U;
+        std::uint32_t minimum = 0U;
+        if (first >= 0xC2U && first <= 0xDFU) {
+            continuation_count = 1U;
+            code_point = first & 0x1FU;
+            minimum = 0x80U;
+        } else if (first >= 0xE0U && first <= 0xEFU) {
+            continuation_count = 2U;
+            code_point = first & 0x0FU;
+            minimum = 0x800U;
+        } else if (first >= 0xF0U && first <= 0xF4U) {
+            continuation_count = 3U;
+            code_point = first & 0x07U;
+            minimum = 0x10000U;
+        } else {
+            return false;
+        }
+        if (index + continuation_count >= text.size()) {
+            return false;
+        }
+        for (std::size_t offset = 1U; offset <= continuation_count; ++offset) {
+            const auto continuation =
+                static_cast<unsigned char>(text[index + offset]);
+            if ((continuation & 0xC0U) != 0x80U) {
+                return false;
+            }
+            code_point = (code_point << 6U) | (continuation & 0x3FU);
+        }
+        if (code_point < minimum || code_point > 0x10FFFFU ||
+            (code_point >= 0xD800U && code_point <= 0xDFFFU)) {
+            return false;
+        }
+        index += continuation_count + 1U;
+    }
+    return true;
+}
+
+std::size_t line_at_offset(
+    const std::string_view text,
+    const std::size_t offset) {
+    return 1U + static_cast<std::size_t>(std::ranges::count(
+                    text.substr(0U, offset), '\n'));
+}
+
+std::vector<std::string_view> required_columns(
+    const ReferenceQuantity quantity) {
+    switch (quantity) {
+        case ReferenceQuantity::displacement:
+            return {
+                node_column,
+                "U-U1",
+                "U-U2",
+                "U-U3",
+                "UR-UR1",
+                "UR-UR2",
+                "UR-UR3",
+            };
+        case ReferenceQuantity::reaction:
+            return {
+                node_column,
+                "RF-RF1",
+                "RF-RF2",
+                "RF-RF3",
+                "RM-RM1",
+                "RM-RM2",
+                "RM-RM3",
+            };
+        case ReferenceQuantity::internal_force:
+            return {
+                element_column,
+                node_column,
+                "SF-SF1",
+                "SF-SF2",
+                "SF-SF3",
+                "SM-SM1",
+                "SM-SM2",
+                "SM-SM3",
+            };
+        case ReferenceQuantity::centroid_stress:
+            return {element_column, node_column, "Sxx"};
+    }
+    return {};
+}
+
+std::vector<std::string_view> value_columns(
+    const ReferenceQuantity quantity) {
+    switch (quantity) {
+        case ReferenceQuantity::displacement:
+            return {"U-U1", "U-U2", "U-U3", "UR-UR1", "UR-UR2", "UR-UR3"};
+        case ReferenceQuantity::reaction:
+            return {"RF-RF1", "RF-RF2", "RF-RF3", "RM-RM1", "RM-RM2", "RM-RM3"};
+        case ReferenceQuantity::internal_force:
+            return {"SF-SF1", "SF-SF2", "SF-SF3", "SM-SM1", "SM-SM2", "SM-SM3"};
+        case ReferenceQuantity::centroid_stress:
+            return {"Sxx"};
+    }
+    return {};
+}
+
+bool parse_positive_label(
+    std::string_view text,
+    std::int64_t& value) {
+    if (text.starts_with('+')) {
+        text.remove_prefix(1U);
+    }
+    const auto parsed = std::from_chars(
+        text.data(), text.data() + text.size(), value);
+    return !text.empty() && parsed.ec == std::errc{} &&
+           parsed.ptr == text.data() + text.size() && value > 0;
+}
+
+bool parse_finite_double(std::string_view text, double& value) {
+    if (text.starts_with('+')) {
+        text.remove_prefix(1U);
+    }
+    const auto parsed = std::from_chars(
+        text.data(),
+        text.data() + text.size(),
+        value,
+        std::chars_format::general);
+    return !text.empty() && parsed.ec == std::errc{} &&
+           parsed.ptr == text.data() + text.size() &&
+           std::isfinite(value);
+}
+
+}  // namespace
+
+ReferenceCsvReadResult read_reference_csv(
+    const ReferenceQuantity quantity,
+    const std::filesystem::path& path,
+    const std::string_view single_instance_name) {
+    std::ifstream file{path, std::ios::binary};
+    if (!file) {
+        return failure(
+            DiagnosticStage::io,
+            "validation.reference_csv_open_failed",
+            "Unable to open reference CSV file.",
+            path,
+            0U);
+    }
+
+    std::string bytes{
+        std::istreambuf_iterator<char>{file},
+        std::istreambuf_iterator<char>{},
+    };
+    if (file.bad()) {
+        return failure(
+            DiagnosticStage::io,
+            "validation.reference_csv_read_failed",
+            "Failed while reading reference CSV file.",
+            path,
+            0U);
+    }
+
+    constexpr std::string_view bom{"\xEF\xBB\xBF"};
+    if (bytes.starts_with(bom)) {
+        bytes.erase(0U, bom.size());
+    }
+    const std::size_t misplaced_bom = bytes.find(bom);
+    if (misplaced_bom != std::string::npos || !is_valid_utf8(bytes)) {
+        return validation_failure(
+            "validation.reference_csv_invalid_encoding",
+            "Reference CSV must be UTF-8 with an optional BOM only at the file start.",
+            path,
+            misplaced_bom == std::string::npos
+                ? 1U
+                : line_at_offset(bytes, misplaced_bom));
+    }
+
+    std::istringstream input{bytes};
+    std::string line;
+    if (!std::getline(input, line)) {
+        return validation_failure(
+            "validation.reference_csv_missing_header",
+            "Reference CSV is missing its header row.",
+            path,
+            1U);
+    }
+
+    const std::vector<std::string> headers = split_fields(line);
+    ColumnIndices column_indices;
+    for (std::size_t index = 0U; index < headers.size(); ++index) {
+        if (headers[index].empty() ||
+            !column_indices.emplace(headers[index], index).second) {
+            return validation_failure(
+                "validation.reference_csv_duplicate_column",
+                "Reference CSV contains an empty or duplicate column name.",
+                path,
+                1U);
+        }
+    }
+
+    const std::vector<std::string_view> required = required_columns(quantity);
+    for (const std::string_view name : required) {
+        if (!column_indices.contains(name)) {
+            return validation_failure(
+                "validation.reference_csv_missing_column",
+                "Reference CSV is missing required column '" +
+                    std::string{name} + "'.",
+                path,
+                1U);
+        }
+    }
+    const bool has_instance = column_indices.contains(instance_column);
+    if (!has_instance && single_instance_name.empty()) {
+        return validation_failure(
+            "validation.reference_csv_missing_column",
+            "Reference CSV omits 'Part Instance Name' without a single-Instance name.",
+            path,
+            1U);
+    }
+
+    std::set<std::string, std::less<>> allowed_columns;
+    allowed_columns.emplace(instance_column);
+    for (const std::string_view name : required) {
+        allowed_columns.emplace(name);
+    }
+    for (const std::string& header : headers) {
+        if (!allowed_columns.contains(header)) {
+            return validation_failure(
+                "validation.reference_csv_unsupported_column",
+                "Reference CSV contains unsupported column '" + header + "'.",
+                path,
+                1U);
+        }
+    }
+
+    const std::vector<std::string_view> components = value_columns(quantity);
+    std::vector<ReferenceRow> rows;
+    std::set<PositionKey> positions;
+    std::size_t line_number = 1U;
+    while (std::getline(input, line)) {
+        ++line_number;
+        if (trim(line).empty()) {
+            continue;
+        }
+        const std::vector<std::string> fields = split_fields(line);
+        if (fields.size() != headers.size()) {
+            return validation_failure(
+                "validation.reference_csv_invalid_row",
+                "Reference CSV row field count does not match the header.",
+                path,
+                line_number);
+        }
+
+        std::string instance_name = has_instance
+                                        ? fields[column_index(
+                                              column_indices,
+                                              instance_column)]
+                                        : std::string{single_instance_name};
+        if (instance_name.empty()) {
+            return validation_failure(
+                "validation.reference_csv_invalid_row",
+                "Reference CSV row has an empty Instance name.",
+                path,
+                line_number);
+        }
+
+        std::int64_t entity_label = 0;
+        const std::string_view entity_column =
+            quantity == ReferenceQuantity::displacement ||
+                    quantity == ReferenceQuantity::reaction
+                ? node_column
+                : element_column;
+        if (!parse_positive_label(
+                fields[column_index(column_indices, entity_column)],
+                entity_label)) {
+            return validation_failure(
+                "validation.reference_csv_invalid_number",
+                "Reference CSV entity label must be a positive integer.",
+                path,
+                line_number);
+        }
+
+        std::optional<std::int64_t> end_node_label;
+        if (quantity == ReferenceQuantity::internal_force ||
+            quantity == ReferenceQuantity::centroid_stress) {
+            std::int64_t parsed_end_node = 0;
+            if (!parse_positive_label(
+                    fields[column_index(column_indices, node_column)],
+                    parsed_end_node)) {
+                return validation_failure(
+                    "validation.reference_csv_invalid_number",
+                    "Reference CSV end-node label must be a positive integer.",
+                    path,
+                    line_number);
+            }
+            end_node_label = parsed_end_node;
+        }
+
+        std::vector<double> values;
+        values.reserve(components.size());
+        for (const std::string_view component : components) {
+            double value = 0.0;
+            if (!parse_finite_double(
+                    fields[column_index(column_indices, component)],
+                    value)) {
+                return validation_failure(
+                    "validation.reference_csv_invalid_number",
+                    "Reference CSV component '" + std::string{component} +
+                        "' must be a finite number.",
+                    path,
+                    line_number);
+            }
+            values.push_back(value);
+        }
+
+        PositionKey key{instance_name, entity_label, end_node_label};
+        if (!positions.insert(key).second) {
+            return validation_failure(
+                "validation.reference_csv_duplicate_row",
+                "Reference CSV contains a duplicate result position.",
+                path,
+                line_number);
+        }
+        rows.push_back({
+            quantity,
+            {std::move(instance_name), entity_label, end_node_label},
+            std::move(values),
+        });
+    }
+    if (input.bad()) {
+        return failure(
+            DiagnosticStage::io,
+            "validation.reference_csv_read_failed",
+            "Failed while reading reference CSV file.",
+            path,
+            line_number);
+    }
+    if (rows.empty()) {
+        return validation_failure(
+            "validation.reference_csv_missing_rows",
+            "Reference CSV contains no result rows.",
+            path,
+            line_number);
+    }
+    return {std::move(rows), {}};
+}
+
+}  // namespace fesa
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 471cca5..56f1971 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -746,6 +746,7 @@ set_property(
 
 add_executable(fesa_validation_comparison_tests
     unit/validation/comparison_test.cpp
+    unit/validation/reference_csv_test.cpp
 )
 
 target_compile_features(
@@ -754,6 +755,11 @@ target_compile_features(
 target_compile_options(
     fesa_validation_comparison_tests PRIVATE /W4 /permissive- /EHsc
 )
+target_compile_definitions(
+    fesa_validation_comparison_tests
+    PRIVATE
+        FESA_TEST_SOURCE_DIR="${CMAKE_CURRENT_SOURCE_DIR}"
+)
 target_link_libraries(
     fesa_validation_comparison_tests
     PRIVATE
@@ -772,3 +778,21 @@ add_test(
     COMMAND "$<TARGET_FILE:fesa_validation_comparison_tests>"
         --gtest_filter=EntityMatching.*
 )
+
+add_test(
+    NAME ReferenceCsv
+    COMMAND "$<TARGET_FILE:fesa_validation_comparison_tests>"
+        --gtest_filter=ReferenceCsv.*
+)
+
+add_test(
+    NAME InternalForceCsv
+    COMMAND "$<TARGET_FILE:fesa_validation_comparison_tests>"
+        --gtest_filter=InternalForceCsv.*
+)
+
+add_test(
+    NAME StressCsv
+    COMMAND "$<TARGET_FILE:fesa_validation_comparison_tests>"
+        --gtest_filter=StressCsv.*
+)
diff --git a/tests/fixtures/reference/internalforces.csv b/tests/fixtures/reference/internalforces.csv
new file mode 100644
index 0000000..712cb44
--- /dev/null
+++ b/tests/fixtures/reference/internalforces.csv
@@ -0,0 +1,3 @@
+Part Instance Name, Element Label, Node Label, SF-SF1, SF-SF2, SF-SF3, SM-SM1, SM-SM2, SM-SM3
+ Part-1-1 , 501 , 101 , 1.25 , -2.5 , 3.75 , -4.0 , 5.5 , -6.25
+ Part-1-1 , 501 , 102 , 7.0 , 8.0 , 9.0 , 10.0 , 11.0 , 12.0
diff --git a/tests/fixtures/reference/stresses.csv b/tests/fixtures/reference/stresses.csv
new file mode 100644
index 0000000..015b458
--- /dev/null
+++ b/tests/fixtures/reference/stresses.csv
@@ -0,0 +1,3 @@
+Element Label, Node Label, Sxx
+501, 101, 42.5
+501, 102, -17.25
diff --git a/tests/unit/validation/reference_csv_test.cpp b/tests/unit/validation/reference_csv_test.cpp
new file mode 100644
index 0000000..6b896cb
--- /dev/null
+++ b/tests/unit/validation/reference_csv_test.cpp
@@ -0,0 +1,235 @@
+#include <gtest/gtest.h>
+
+#include <algorithm>
+#include <filesystem>
+#include <fstream>
+#include <stdexcept>
+#include <string>
+#include <string_view>
+#include <system_error>
+#include <vector>
+
+#include <fesa/validation/reference_csv.hpp>
+
+namespace {
+
+class TemporaryCsv final {
+public:
+    TemporaryCsv(std::string_view name, std::string_view contents)
+        : path_{std::filesystem::path{testing::TempDir()} / name} {
+        std::ofstream output{path_, std::ios::binary};
+        output.write(
+            contents.data(), static_cast<std::streamsize>(contents.size()));
+        if (!output) {
+            throw std::runtime_error{"Failed to write temporary reference CSV."};
+        }
+    }
+
+    ~TemporaryCsv() {
+        std::error_code error;
+        std::filesystem::remove(path_, error);
+    }
+
+    TemporaryCsv(const TemporaryCsv&) = delete;
+    TemporaryCsv& operator=(const TemporaryCsv&) = delete;
+
+    [[nodiscard]] const std::filesystem::path& path() const noexcept {
+        return path_;
+    }
+
+private:
+    std::filesystem::path path_;
+};
+
+std::filesystem::path fixture_path(const std::string_view name) {
+    return std::filesystem::path{FESA_TEST_SOURCE_DIR} / "fixtures" /
+           "reference" / name;
+}
+
+std::filesystem::path supplied_reference_path(const std::string_view name) {
+    return std::filesystem::path{FESA_TEST_SOURCE_DIR}.parent_path() /
+           "reference" / "cantilever beam" / name;
+}
+
+bool has_diagnostic(
+    const std::vector<fesa::Diagnostic>& diagnostics,
+    const std::string_view code) {
+    return std::ranges::any_of(
+        diagnostics,
+        [code](const fesa::Diagnostic& diagnostic) {
+            return diagnostic.code == code;
+        });
+}
+
+TEST(ReferenceCsv, ReadsSuppliedDisplacementsWithWhitespaceHeader) {
+    const auto result = fesa::read_reference_csv(
+        fesa::ReferenceQuantity::displacement,
+        supplied_reference_path("cantilever beam displacements.csv"),
+        "Part-1-1");
+
+    ASSERT_TRUE(result.diagnostics.empty());
+    ASSERT_EQ(result.rows.size(), 11U);
+    EXPECT_EQ(
+        result.rows.front().quantity,
+        fesa::ReferenceQuantity::displacement);
+    EXPECT_EQ(result.rows.front().position.instance_name, "Part-1-1");
+    EXPECT_EQ(result.rows.front().position.entity_label, 1);
+    EXPECT_FALSE(result.rows.front().position.end_node_label.has_value());
+    EXPECT_EQ(
+        result.rows.front().values,
+        (std::vector<double>{0.0, 0.0, -1.0e-32, 0.0, 1.0e-31, 0.0}));
+    EXPECT_EQ(result.rows.back().position.entity_label, 11);
+    EXPECT_EQ(result.rows.back().values[2], -1.92e-4);
+}
+
+TEST(ReferenceCsv, ReadsSuppliedReactionsWithWhitespaceHeader) {
+    const auto result = fesa::read_reference_csv(
+        fesa::ReferenceQuantity::reaction,
+        supplied_reference_path("cantilever beam reactions.csv"),
+        "Part-1-1");
+
+    ASSERT_TRUE(result.diagnostics.empty());
+    ASSERT_EQ(result.rows.size(), 11U);
+    EXPECT_EQ(result.rows.front().position.instance_name, "Part-1-1");
+    EXPECT_EQ(result.rows.front().position.entity_label, 1);
+    EXPECT_FALSE(result.rows.front().position.end_node_label.has_value());
+    EXPECT_EQ(
+        result.rows.front().values,
+        (std::vector<double>{0.0, 0.0, 1.0e4, 0.0, -1.0e5, 0.0}));
+}
+
+TEST(InternalForceCsv, MapsAllSixComponentsAndElementEndPosition) {
+    const auto result = fesa::read_reference_csv(
+        fesa::ReferenceQuantity::internal_force,
+        fixture_path("internalforces.csv"),
+        "unused-request-name");
+
+    ASSERT_TRUE(result.diagnostics.empty());
+    ASSERT_EQ(result.rows.size(), 2U);
+    EXPECT_EQ(
+        result.rows.front().quantity,
+        fesa::ReferenceQuantity::internal_force);
+    EXPECT_EQ(result.rows.front().position.instance_name, "Part-1-1");
+    EXPECT_EQ(result.rows.front().position.entity_label, 501);
+    ASSERT_TRUE(result.rows.front().position.end_node_label.has_value());
+    EXPECT_EQ(*result.rows.front().position.end_node_label, 101);
+    EXPECT_EQ(
+        result.rows.front().values,
+        (std::vector<double>{1.25, -2.5, 3.75, -4.0, 5.5, -6.25}));
+}
+
+TEST(StressCsv, FillsOmittedInstanceAndReadsCentroidStress) {
+    const auto result = fesa::read_reference_csv(
+        fesa::ReferenceQuantity::centroid_stress,
+        fixture_path("stresses.csv"),
+        "Part-1-1");
+
+    ASSERT_TRUE(result.diagnostics.empty());
+    ASSERT_EQ(result.rows.size(), 2U);
+    EXPECT_EQ(result.rows.front().position.instance_name, "Part-1-1");
+    EXPECT_EQ(result.rows.front().position.entity_label, 501);
+    ASSERT_TRUE(result.rows.front().position.end_node_label.has_value());
+    EXPECT_EQ(*result.rows.front().position.end_node_label, 101);
+    EXPECT_EQ(result.rows.front().values, (std::vector<double>{42.5}));
+    EXPECT_EQ(result.rows.back().values, (std::vector<double>{-17.25}));
+}
+
+TEST(ReferenceCsv, AcceptsUtf8BomOnlyAtTheStartAndTrimsValues) {
+    const TemporaryCsv input{
+        "fesa-reference-bom.csv",
+        "\xEF\xBB\xBF Part Instance Name , Node Label , U-U1 , U-U2 , "
+        "U-U3 , UR-UR1 , UR-UR2 , UR-UR3\n"
+        " Beam-1 , 7 , 1 , 2 , 3 , 4 , 5 , 6 \n"};
+
+    const auto result = fesa::read_reference_csv(
+        fesa::ReferenceQuantity::displacement, input.path(), "unused");
+
+    ASSERT_TRUE(result.diagnostics.empty());
+    ASSERT_EQ(result.rows.size(), 1U);
+    EXPECT_EQ(result.rows[0].position.instance_name, "Beam-1");
+    EXPECT_EQ(result.rows[0].position.entity_label, 7);
+    EXPECT_EQ(
+        result.rows[0].values,
+        (std::vector<double>{1.0, 2.0, 3.0, 4.0, 5.0, 6.0}));
+}
+
+TEST(ReferenceCsv, DiagnosesMissingRequiredColumn) {
+    const TemporaryCsv input{
+        "fesa-reference-missing-column.csv",
+        "Node Label,U-U1,U-U2,U-U3,UR-UR1,UR-UR2,Unexpected\n"
+        "1,0,0,0,0,0,0\n"};
+
+    const auto result = fesa::read_reference_csv(
+        fesa::ReferenceQuantity::displacement, input.path(), "Part-1-1");
+
+    EXPECT_TRUE(result.rows.empty());
+    ASSERT_TRUE(has_diagnostic(
+        result.diagnostics, "validation.reference_csv_missing_column"));
+    ASSERT_TRUE(result.diagnostics.front().source.has_value());
+    EXPECT_EQ(result.diagnostics.front().source->line, 1U);
+}
+
+TEST(ReferenceCsv, DiagnosesDuplicateResultPosition) {
+    const TemporaryCsv input{
+        "fesa-reference-duplicate.csv",
+        "Element Label,Node Label,Sxx\n"
+        "8,2,10\n"
+        "8,2,11\n"};
+
+    const auto result = fesa::read_reference_csv(
+        fesa::ReferenceQuantity::centroid_stress,
+        input.path(),
+        "Part-1-1");
+
+    EXPECT_TRUE(result.rows.empty());
+    ASSERT_TRUE(has_diagnostic(
+        result.diagnostics, "validation.reference_csv_duplicate_row"));
+    ASSERT_TRUE(result.diagnostics.front().source.has_value());
+    EXPECT_EQ(result.diagnostics.front().source->line, 3U);
+}
+
+TEST(ReferenceCsv, DiagnosesInvalidAndNonfiniteNumbers) {
+    const TemporaryCsv invalid{
+        "fesa-reference-invalid-number.csv",
+        "Node Label,RF-RF1,RF-RF2,RF-RF3,RM-RM1,RM-RM2,RM-RM3\n"
+        "1,0,0,not-a-number,0,0,0\n"};
+    const TemporaryCsv nonfinite{
+        "fesa-reference-nonfinite-number.csv",
+        "Element Label,Node Label,Sxx\n"
+        "8,2,nan\n"};
+
+    const auto invalid_result = fesa::read_reference_csv(
+        fesa::ReferenceQuantity::reaction,
+        invalid.path(),
+        "Part-1-1");
+    const auto nonfinite_result = fesa::read_reference_csv(
+        fesa::ReferenceQuantity::centroid_stress,
+        nonfinite.path(),
+        "Part-1-1");
+
+    EXPECT_TRUE(invalid_result.rows.empty());
+    EXPECT_TRUE(nonfinite_result.rows.empty());
+    EXPECT_TRUE(has_diagnostic(
+        invalid_result.diagnostics,
+        "validation.reference_csv_invalid_number"));
+    EXPECT_TRUE(has_diagnostic(
+        nonfinite_result.diagnostics,
+        "validation.reference_csv_invalid_number"));
+}
+
+TEST(ReferenceCsv, RejectsUtf8BomOutsideTheFileStart) {
+    const TemporaryCsv input{
+        "fesa-reference-misplaced-bom.csv",
+        "Node Label,\xEF\xBB\xBF U-U1,U-U2,U-U3,UR-UR1,UR-UR2,UR-UR3\n"
+        "1,0,0,0,0,0,0\n"};
+
+    const auto result = fesa::read_reference_csv(
+        fesa::ReferenceQuantity::displacement, input.path(), "Part-1-1");
+
+    EXPECT_TRUE(result.rows.empty());
+    EXPECT_TRUE(has_diagnostic(
+        result.diagnostics,
+        "validation.reference_csv_invalid_encoding"));
+}
+
+}  // namespace