Editors. "Bulgarians are forced to withdraw from Serbia". The Literary Encyclopedia. First published 30 December 2011
[http://www.litencyc.com/php/stopics.php?rec=true&UID=18923, accessed 24 May 2013.]
Following the union of Bulgaria with Eastern Rumelia, Serbia has launched an invasion of Bulgarian territory, but has been speedily defeated and humiliated. Now the Bulgarians launch a counter-invasion of their own and take the town of Pirot in south-eastern Serbia, but the intervention of Austria forces them to withdraw.