Columbia subject headings:
Haskins, Charles Homer, 1870-1937--Congresses.
Twelfth century--Congresses.
Harvard subject headings:
Civilization, Medieval--12th century--Congresses.
Haskins, Charles Homer, 1870-1937--Congresses.
Twelfth century--Congresses.
Princeton subject headings:
Haskins, Charles Homer, 1870-1937--Congresses.
Twelfth century--Congresses.