Columbia subject headings:
Catholic Church--Relations--Periodicals.
Christian union--Periodicals.
Ecumenical movement--Periodicals.
Religion--Periodicals.
Harvard subject headings:
Catholic Church--Relations--Periodicals.
Christian union--Periodicals.
Ecumenical movement--Periodicals.
Religion--Periodicals
Princeton subject headings:
Catholic Church--Relations--Periodicals.
Christian union--Periodicals.
Ecumenical movement--Periodicals.
Periodicals.
Religion--Periodicals.