Columbia subject headings:
Algebraic topology.
Geometry, Algebraic.
Lefschetz, Solomon, 1884-1972.
Harvard subject headings:
Algebraic topology.
Geometry, Algebraic.
Lefschetz, Solomon, 1884-1972
Topology.
Princeton subject headings:
Algebraic topology.
Geometry, Algebraic.
Lefschetz, Solomon, 1884-1972.