Columbia subject headings:
Christianity--Europe--History--Congresses.
Europe--Religion--Congresses.
Secularization--Europe--History--Congresses.
Harvard subject headings:
Christianity--Europe--Congresses
Christianity--Europe--History.
Europe--Religion--Congresses.
Europe--Religion--History.
Secularism--Europe--History--Congresses.
Secularization--Europe--History.
Princeton subject headings:
Christianity--Europe--Congresses.
Europe--Religion--Congresses.
Secularism--Europe--History--Congresses.