Flag of the Chernoyevitch Dynasty, based on it's coat of arms and a written description from a Venetian diplomatic corespondance:
Noble coat of arms was granted to Ivan Chernoyevitch on the assembly of the Great council of Venice, 24.02.1473, which is attested to by the golden bull, whose transcript is kept in the State Archive of Venice (Arcshivio di Stato di Venezia, Ex libro privilegiorum II, ch. 54), in which the eagle is described as a golden two-headed eagle. (Source: A. Samardžić, "Dosadašnji izvori o grbovima Crnojevića" MATICA, 2010, p. 762) (original text in Montenegrin/Serbo-Croatian)
The designed of the eagle itself is based on the printed coat of arms on the first page of Cetinje Octoechos, a South Slavic liturgy book, printed in Montenegro in 1494, by the Crnojević printing house.

The red field of the flag is attested by Charles du Fresne Sieur du Cange, who states "And after the fall of Montenegro, the heraldic tradition was carried out by Staniša Crnojević, as well as his grandchildren, which went into exile in Venice. Members of house Crnojević, which were accepted into the ranks of Venetian nobility, carried a golden two-headed eagle on a red field" (Source: Charles du Fresne Sieur du Cange, Illyricum vetus et novum, p. 135) (original text in Latin).
Own work
Germenfer