Todor Balabanov (2001)
Za smisǔla na edin grǔtski nadpis ot manastira pri s. Chernoglavtsi, Shumensko
In: Izsledvaniya v chest na prof. d.ist.n. Totyu Totev, ed. by Vasil GYUZELEV and Khristo TRENDAFILOV. Akademichno izdatelstvo "Prof. Marin Drinov", Sofiya, pp. 107-112.
Argues that the cross-sign in the centre of a text at the central entrance of the monastery church stands for Christ defeating the power of the Dragon, and associates it with the precepts found in Kosmas the Priest's Beseda protiv bogomilite.