Correct bug again

scipost/utils.py

@@ -391,7 +391,7 @@ class Utils(object):
                 'Your work has been cited in a paper published by SciPost,'
                 '\n\n' + cls.invitation.cited_in_publication.title 
                 + ' by ' + cls.invitation.cited_in_publication.author_list + 
-                '\n\n(published as ' + cls.invitation.cited_in_publication.citation
+                '\n\n(published as ' + cls.invitation.cited_in_publication.citation()
                 + ').\n\n'
                 'I would hereby like to use this opportunity to quickly introduce '
                 'you to the SciPost initiative, and to invite you to become an active '
@@ -408,7 +408,7 @@ class Utils(object):
             email_context['pub_title'] = cls.invitation.cited_in_publication.title 
             email_context['pub_author_list'] = cls.invitation.cited_in_publication.author_list
             email_context['doi_label'] = cls.invitation.cited_in_publication.doi_label
-            email_context['citation'] = cls.invitation.cited_in_publication.citation
+            email_context['citation'] = cls.invitation.cited_in_publication.citation()
             email_text += summary_text
             email_text_html += summary_text_html
             email_text_html += '<br/>' + EMAIL_FOOTER