+    def add_to_zip(self, zipf, student=False, prefix=''):
+        zipf.write(self.xml_file.path,
+            "%spliki-zrodlowe/%s.xml" % (prefix, self.slug))
+        pdf = self.student_pdf if student else self.pdf
+        if pdf:
+            zipf.write(self.xml_file.path, 
+                "%s%s%s.pdf" % (prefix, self.slug, "_student" if student else ""))
+        
+