Columbia subject headings:
Mystical union--Early works to 1800.
Orthodox Eastern Church--Doctrines--Early works to 1800.
Sacraments--Orthodox Eastern Church--Early works to 1800.
Harvard subject headings:
Mystical union--Early works to 1800.
Orthodox Eastern Church--Doctrines--Early works to 1800.
Sacraments--Orthodox Eastern Church--Early works to 1800.
Princeton subject headings:
Mystical union.
Orthodox Eastern Church--Doctrines.
Sacraments--Orthodox Eastern Church.