diff --git a/lib/Controllers/DefaultController.php b/lib/Controllers/DefaultController.php
index 80cf87c..58f5219 100644
--- a/lib/Controllers/DefaultController.php
+++ b/lib/Controllers/DefaultController.php
@@ -499,18 +499,20 @@ class DefaultController extends ControllerAbstract {
     // ==================== Entity Operations ====================
 
     private function entityListBulk(string $tenantId, string $userId, array $data): mixed {
-        if (!isset($data['sources'])) {
-            throw new InvalidArgumentException(self::ERR_MISSING_SOURCES);
-        }
-        if (!is_array($data['sources'])) {
-            throw new InvalidArgumentException(self::ERR_INVALID_SOURCES);
-        }
         
-        $sources = ResourceIdentifiers::fromArray($data['sources']);
-        foreach ($sources as $source) {
-            if (!$source instanceof EntityIdentifier) {
-                throw new InvalidArgumentException('Invalid parameter: sources must contain provider:service:collection:entity identifiers');
+        if (isset($data['sources'])) {
+            if (!is_array($data['sources'])) {
+                throw new InvalidArgumentException(self::ERR_INVALID_SOURCES);
             }
+
+            $sources = ResourceIdentifiers::fromArray($data['sources']);
+            foreach ($sources as $source) {
+                if (!$source instanceof ServiceIdentifier && !$source instanceof CollectionIdentifier) {
+                    throw new InvalidArgumentException('Invalid parameter: sources must contain provider:service or provider:service:collection identifiers');
+                }
+            }
+        } else {
+            $sources = null;
         }
         
 		$filter = $data['filter'] ?? null;
@@ -522,19 +524,22 @@ class DefaultController extends ControllerAbstract {
     }
 
     private function entityListStream(string $tenantId, string $userId, array $data, int $version, string $transaction): StreamedNdJsonResponse {
-        if (!isset($data['sources'])) {
-            throw new InvalidArgumentException(self::ERR_MISSING_SOURCES);
-        }
-        if (!is_array($data['sources'])) {
-            throw new InvalidArgumentException(self::ERR_INVALID_SOURCES);
+        
+        if (isset($data['sources'])) {
+            if (!is_array($data['sources'])) {
+                throw new InvalidArgumentException(self::ERR_INVALID_SOURCES);
+            }
+
+            $sources = ResourceIdentifiers::fromArray($data['sources']);
+            foreach ($sources as $source) {
+                if (!$source instanceof ServiceIdentifier && !$source instanceof CollectionIdentifier) {
+                    throw new InvalidArgumentException('Invalid parameter: sources must contain provider:service or provider:service:collection identifiers');
+                }
+            }
+        } else {
+            $sources = null;
         }
 
-        $sources = ResourceIdentifiers::fromArray($data['sources']);
-        foreach ($sources as $source) {
-            if (!$source instanceof ServiceIdentifier && !$source instanceof CollectionIdentifier) {
-                throw new InvalidArgumentException('Invalid parameter: sources must contain provider:service or provider:service:collection identifiers');
-            }
-        }
 
         $filter = $data['filter'] ?? null;
         $sort   = $data['sort'] ?? null;