diff -r 31a4987f6017 -r 226d5b17a119 server/src/app/Models/DocumentBase.php
--- a/server/src/app/Models/DocumentBase.php	Sun Oct 09 11:44:18 2016 +0200
+++ b/server/src/app/Models/DocumentBase.php	Tue Oct 11 02:49:59 2016 +0200
@@ -26,8 +26,8 @@
     // memoization
     private $providedCHO = null;
     private $title = false;
-    private $lang = null;
-    private $langResolved = null;
+    private $langs = null;
+    private $langsResolved = null;
     private $issued = false;
     private $modified = false;
     private $created = false;
@@ -43,8 +43,8 @@
     protected function clearMemoizationCache() {
         $this->providedCHO = null;
         $this->title = false;
-        $this->lang = null;
-        $this->langResolved = null;
+        $this->langs = null;
+        $this->langsResolved = null;
         $this->issued = false;
         $this->modified = false;
         $this->created = false;
@@ -65,36 +65,33 @@
         return $this->id;
     }
 
-    public function getLanguage() {
-        if(is_null($this->lang)) {
+    public function getLanguages() {
+        if(is_null($this->langs)) {
             try {
-                $langs = $this->getProvidedCHO()->all('<http://purl.org/dc/elements/1.1/language>');
-                if(count($langs) > 0) {
-                    $this->lang = $langs[0];
-                }
+                $this->langs = $this->getProvidedCHO()->all('<http://purl.org/dc/elements/1.1/language>');
             } catch(\Exception $e) {
-                $this->lang = null;
+                $this->langs = [];
             }
         }
-        return $this->lang;
+        return $this->langs;
     }
 
-    public function getLanguageValue() {
-        $lang = $this->getLanguage();
-        if($lang instanceof Resource) {
-            return $lang->getUri();
-        } else if($lang instanceof Literal) {
-            return $lang->getValue();
-        }
-        return null;
+    public function getLanguagesValue() {
+        return array_map(function($lang) {
+            if($lang instanceof Resource) {
+                return $lang->getUri();
+            } else if($lang instanceof Literal) {
+                return $lang->getValue();
+            }
+        }, $this->getLanguages());
     }
 
-    public function getLanguageResolved() {
-        return $this->langResolved;
+    public function getLanguagesResolved() {
+        return $this->langsResolved;
     }
 
-    public function setLanguageResolved($languageResolved) {
-        $this->langResolved = $languageResolved;
+    public function setLanguagesResolved($languagesResolved) {
+        $this->langsResolved = $languagseResolved;
     }
 
 
@@ -181,7 +178,7 @@
             $newModified = new Literal($value, null, "http://purl.org/dc/terms/W3CDTF");
             $this->setSimpleProperty($this->getProvidedCHO(), 'http://purl.org/dc/terms/modified', $modified, $newModified);
 
-            $this->modified = null;
+            $this->modified = false;
         }
     }
 
@@ -202,12 +199,12 @@
                 'id' => $this->getId(),
                 'uri' => $this->getUri(),
                 'title' => $this->getTitleValue(),
-                'language' => $this->getLanguageValue(),
+                'languages' => $this->getLanguagesValue(),
                 'modified' => $this->getModifiedValue(),
                 'issued' => $this->getIssuedValue()            ];
 
-            if($this->language_resolved) {
-                $res['language_resolved'] = $this->getLanguageResolved();
+            if($this->languagesResolved) {
+                $res['languages_resolved'] = $this->getLanguagesResolved();
             }
 
             return $res;