diff --git a/xml/schema/catalog.xml b/xml/schema/catalog.xml
index 0944bcf..e36e97d 100644
--- a/xml/schema/catalog.xml
+++ b/xml/schema/catalog.xml
@@ -22,6 +22,8 @@
 
  <!-- Expression Schemas -->
 
+ <system systemId="http://www.entrouvert.org/expression/schemas/Article.xsd"
+         uri="Article.xsd"/>
  <system systemId="http://www.entrouvert.org/expression/schemas/Configuration.xsd"
          uri="Configuration.xsd"/>
  <system systemId="http://www.entrouvert.org/expression/schemas/DbXmlDocumentResult.xsd"