books.google.bg - Discusses the development of ethnic nationalism among Bulgars, Croatians, Serbians, and Macedonians...http://books.google.bg/books/about/The_Early_Medieval_Balkans.html?hl=bg&id=Y0NBxG9Id58C&q=Thus+by+Peter's+reign+the+Bulgar+and+Slavic+elements+had+merged+to+form+a+Slavic&utm_source=gb-gplus-share“The” Early Medieval Balkans
