Columbia subject headings:
Hymns, Church Slavic--Congresses.
Orthodox Eastern Church--Hymns--Congresses.
Harvard subject headings:
Byzantine chants--History and criticism--Congresses.
Hymns, Church Slavic--History and criticism--Congresses.
Music, Byzantine--History and criticism--Congresses.
Orthodox Eastern Church--Hymns--History and criticism--Congresses.
Orthodox Eastern Church--Liturgy--Congresses.
Princeton subject headings:
Hymns, Church Slavic--Congresses.
Hymns.
Orthodox Eastern Church--Hymns--Congresses.