Columbia subject headings:
Asceticism--Early works to 1800.
Church of the East--Doctrines.
Isaac, Bishop of Nineveh, active 7th century.
Harvard subject headings:
Asceticism--Early works to 1800.
Isaac, Bishop of Nineveh, active 7th century
Nestorian Church--Doctrines--History.
Princeton subject headings:
Asceticism--Early works to 1800.
Isaac, Bishop of Nineveh, active 7th century.
Nestorian Church--Doctrines.