diff -r 92fc9d077f95 -r 31a4987f6017 server/src/app/Models/DocumentBase.php
--- a/server/src/app/Models/DocumentBase.php	Fri Oct 07 02:07:34 2016 +0200
+++ b/server/src/app/Models/DocumentBase.php	Sun Oct 09 11:44:18 2016 +0200
@@ -28,8 +28,9 @@
     private $title = false;
     private $lang = null;
     private $langResolved = null;
-    private $issued = null;
-    private $modified = null;
+    private $issued = false;
+    private $modified = false;
+    private $created = false;
 
 
     public function getProvidedCHO() {
@@ -44,8 +45,9 @@
         $this->title = false;
         $this->lang = null;
         $this->langResolved = null;
-        $this->issued = null;
-        $this->modified = null;
+        $this->issued = false;
+        $this->modified = false;
+        $this->created = false;
     }
 
     public function getId() {
@@ -125,7 +127,7 @@
     }
 
     public function getIssued() {
-        if(is_null($this->issued)) {
+        if($this->issued === false) {
             try {
                 $this->issued = $this->getProvidedCHO()->getLiteral("<http://purl.org/dc/terms/issued>");
             } catch(\Exception $e) {
@@ -140,8 +142,19 @@
         return is_null($issued)?null:$issued->getValue();
     }
 
+    public function getCreated() {
+        if($this->created === false) {
+            try {
+                $this->created = $this->getProvidedCHO()->getLiteral("<http://purl.org/dc/terms/created>");
+            } catch(\Exception $e) {
+                $this->created = null;
+            }
+        }
+        return $this->created;
+    }
+
     public function getModified() {
-        if(is_null($this->modified)) {
+        if($this->modified === false) {
             try {
                 $this->modified = $this->getProvidedCHO()->getLiteral("<http://purl.org/dc/terms/modified>");
                 if(is_null($this->modified)) {