What is "srbulja"

A srbulјa , srbulje in plural, is a liturgical book written or printed in the Serbo-Slavonic language (the Serbian recension of Church Slavonic), which was the written language of Serbs from the 12th century to the 1830s. The term was used for the first time by Vuk Karadžić in 1816 to differentiate liturgical books written in the Serbian recension from those written in the Russian recension, which gradually replaced srbulje at the beginning of the 19th century.

Until the end of the 15th century srbulje were only written books. Since 1494 ( Cetinje Octoechos) until 1570 several printing houses printed srbulje.