Columbia subject headings:
Bulgarian language--Influence on Russian.
Russian language--1300-1700.
Russian language--To 1300.
Harvard subject headings:
Bulgarian language--Influence on Russian
Church Slavic language--East Slavic recension
Church Slavic language--Russian recension
Russian language--1300-
Russian language--Foreign elements--Church Slavic
Russian language--History.
Russian language--To 1300.
Princeton subject headings:
Church Slavic language--East Slavic recension.
Church Slavic language--Russian recension.
Russian language--Foreign elements--Church Slavic.
Russian language--History.