Zhitie i dei͡atelʹnostʹ izhe vo svi͡atykh ott͡sa nashego Grigorii͡a Sinaita

Callistus II Saint, Patriarch of Constantinople, Russia (Federation). Federalʹnoe agenstvo po obrazovanii︠u︡, Hans-Veit Beyer, Uralʹskiĭ gosudarstvennyĭ universitet im. A.M. Gorʹkogo, Callistus I Patriarch of Constantinople