Columbia subject headings:
Barnabas, Apostle, Saint.
Clamens Romanus.
Fathers of the church.
Hermas, active 2nd century.
Ignatius, Saint, Bishop of Antioch, -approximately 110.
Polycarp, Saint, Bishop of Smyrna.
Harvard subject headings:
Barnabas, Apostle, Saint.
Clement I, Pope.
Fathers of the church.
Hermas, active 2nd century.
Ignatius, Saint, Bishop of Antioch, -approximately 110
Polycarp, Saint, Bishop of Smyrna
Princeton subject headings: