diff --git a/src/MDConcSourceTypes.php b/src/MDConcSourceTypes.php
new file mode 100644
index 0000000..c78f94c
--- /dev/null
+++ b/src/MDConcSourceTypes.php
@@ -0,0 +1,41 @@
+<?PHP
+/**
+ * Constains lists for categorizing source types.
+ *
+ * @author Joshua Ramon Enslin <joshua@museum-digital.de>
+ */
+declare(strict_types = 1);
+
+/**
+ * Provides a list for finding the source type for an input.
+ */
+final class MDConcSourceTypes implements MDImporterConcordanceListInterface {
+
+    private const SOURCE_TYPES = [
+
+        // Book / default
+        "buch" => "book",
+        "literatur" => "book",
+
+    ];
+
+    /**
+     * Require a function for getting the concordance target.
+     *
+     * @param string $input Input string.
+     *
+     * @return string
+     */
+    public static function getConcordanceTarget(string $input):string {
+
+        if (isset(self::SOURCE_TYPES[$input])) {
+            return self::SOURCE_TYPES[$input];
+        }
+        if (isset(self::SOURCE_TYPES[strtolower($input)])) {
+            return self::SOURCE_TYPES[strtolower($input)];
+        }
+
+        throw new MDImporterMissingConcordance("Unknown source type: " . $input);
+
+    }
+}