Columbia subject headings:
Confession--Orthodox Eastern Church--History.
Orthodox Eastern Church--Liturgy.
Orthodox Eastern Church. Euchologion.
Penance--Orthodox Eastern Church--History.
Russkai͡a pravoslavnai͡a t͡serkovʹ. Trēbnik.
Harvard subject headings:
Confession--Eastern Orthodox Church--History.
Orthodox Eastern Church. Euchologion. Church Slavic.
Orthodox Eastern Church. Euchologion. Greek.
Penance--Eastern Orthodox Church--History.
Princeton subject headings:
Confession--Orthodox Eastern Church--History.
Orthodox Eastern Church--Liturgy.
Orthodox Eastern Church. Euchologion
Penance--Orthodox Eastern Church--History.
Russkai︠a︡ pravoslavnai︠a︡ t︠s︡erkovʹ. Trēbnik