Фаддеевна Ковязина, Надежда. “Invariant Entries and Gospel Lections in the Slavic Lectionary Menology of the 11–16th Cc. (September)”. Slavistica Vilnensis, vol. 49, no. 2, Dec. 2000, pp. 51–60, https://doi.org/10.15388/SV.2000.23119.