diff --git a/bib/sivanov-extra.bib b/bib/sivanov-extra.bib
index 12cd489..fa0a578 100644
--- a/bib/sivanov-extra.bib
+++ b/bib/sivanov-extra.bib
@@ -31,5 +31,6 @@ ISBN = {978-952-12-3123-0},
   Author  = {Sergiu Ivanov and Sergey Verlan},
   Journal = {Annals of the University of Bucharest (Informatics)},
   Volume  = {LXII(2)},
-  Pages   = {77--88}
+  Pages   = {77--88},
+  Year    = {2015}
 }