In Ms 29 of the National and University Library in Ljubljana (Slovenia) — an early 13th-century copy of Dialogorum libri IV by Gregory the Great — there are two musical insertions: the sequence Celi solem imitantes and the hymn Jam lucis orto sidere. Written in Hungarian notation they were inserted onto blank pages in the completed manuscript in the span of time from the late 13th to the mid-14th century. Ms 29 bears a marginal inscription referring to Augustinus Cazottus (Kažotić), Bishop of Zagreb in the early 14th century. It was obviously in his possession. Presumably, the sequence and the hymn were inserted into Ms 29 somewhere in the Diocese of Zagreb, by someone skilled in Hungarian notation.