diff --git a/EnvelopeGenerator.Extensions/MemoryCacheExtensions.cs b/EnvelopeGenerator.Extensions/MemoryCacheExtensions.cs
index acecfe86..f9b0a1ac 100644
--- a/EnvelopeGenerator.Extensions/MemoryCacheExtensions.cs
+++ b/EnvelopeGenerator.Extensions/MemoryCacheExtensions.cs
@@ -6,11 +6,20 @@ public static class MemoryCacheExtensions
 {
     private static readonly Guid BaseId = Guid.NewGuid();
 
-    public static IDictionary<string, int> GetEnumAsDictionary<TEnum>(this IMemoryCache memoryCache, string key = "", params IEnumerable<TEnum>[] ignores)
+    public static IDictionary<string, int> GetEnumAsDictionary<TEnum>(this IMemoryCache memoryCache, string key = "", params object[] ignores)
         where TEnum : Enum
         => memoryCache.GetOrCreate(BaseId + typeof(TEnum).FullName + key, _ =>
         {
-            List<TEnum> mergedIgnores = ignores.SelectMany(x => x).ToList();
+            var mergedIgnores = new List<TEnum>();
+
+            foreach (var ignore in ignores)
+            {
+                if (ignore is IEnumerable<TEnum> ignoreList)
+                    mergedIgnores.AddRange(ignoreList);
+                else if (ignore is TEnum ignoreVal)
+                    mergedIgnores.Add(ignoreVal);
+            }
+
             return Enum.GetValues(typeof(TEnum))
                    .Cast<TEnum>()
                    .Where(e => !mergedIgnores.Contains(e))
diff --git a/EnvelopeGenerator.GeneratorAPI/Controllers/HistoryController.cs b/EnvelopeGenerator.GeneratorAPI/Controllers/HistoryController.cs
index d4d4ec2c..a7292e08 100644
--- a/EnvelopeGenerator.GeneratorAPI/Controllers/HistoryController.cs
+++ b/EnvelopeGenerator.GeneratorAPI/Controllers/HistoryController.cs
@@ -18,8 +18,6 @@ namespace EnvelopeGenerator.GeneratorAPI.Controllers;
 [Authorize]
 public class HistoryController : ControllerBase
 {
-    private readonly ILogger<HistoryController> _logger;
-
     private readonly IEnvelopeHistoryService _service;
 
     private readonly IMemoryCache _memoryCache;
@@ -27,11 +25,10 @@ public class HistoryController : ControllerBase
     /// <summary>
     /// Konstruktor für den HistoryController.
     /// </summary>
-    /// <param name="logger">Der Logger, der für das Protokollieren von Informationen verwendet wird.</param>
     /// <param name="service">Der Dienst, der für die Verarbeitung der Umschlaghistorie verantwortlich ist.</param>
-    public HistoryController(ILogger<HistoryController> logger, IEnvelopeHistoryService service, IMemoryCache memoryCache)
+    /// <param name="memoryCache"></param>
+    public HistoryController(IEnvelopeHistoryService service, IMemoryCache memoryCache)
     {
-        _logger = logger;
         _service = service;
         _memoryCache = memoryCache;
     }
@@ -54,7 +51,7 @@ public class HistoryController : ControllerBase
     [Authorize]
     public IActionResult GetReferenceTypes(ReferenceType? referenceType = null)
     {
-        return referenceType is null ? Ok(_memoryCache.GetEnumAsDictionary<ReferenceType>()) : Ok(referenceType.ToString());
+        return referenceType is null ? Ok(_memoryCache.GetEnumAsDictionary<ReferenceType>("gen.api", ReferenceType.Unknown)) : Ok(referenceType.ToString());
     }
 
     /// <summary>