diff --git a/Klausuren/Sda1/2018Summer/Solve/Schema/bib.xsd b/Klausuren/Sda1/2018Summer/Solve/Schema/bib.xsd
index 0a532d7ceb0c294bcfbce17f6f0f3f33a121062b..0a67e4942a460b02fc97f7712f32de408d623496 100644
--- a/Klausuren/Sda1/2018Summer/Solve/Schema/bib.xsd
+++ b/Klausuren/Sda1/2018Summer/Solve/Schema/bib.xsd
@@ -46,7 +46,7 @@
     <xs:complexType>
       <xs:sequence>
         <xs:element ref="title"/>
-        <xs:choice minOccurs="1" maxOccurs="unbounded">
+        <xs:choice maxOccurs="unbounded">
           <xs:element ref="author"/>
           <xs:element ref="editor"/>
         </xs:choice>
@@ -63,7 +63,7 @@
         <xs:element name="uri" >
           <xs:simpleType>
             <xs:restriction base="xs:anyURI">
-              <xs:pattern value="http[s]?://.+"></xs:pattern>
+              <xs:pattern value="http[s]?://.+"/>
             </xs:restriction>
           </xs:simpleType>
         </xs:element>