Columbia subject headings:
Harvard subject headings:
Popper, Karl R. (Karl Raimund), 1902-1994--Congresses.
Rationalism--Congresses.
Social sciences--Philosophy--Congresses
Princeton subject headings:
Popper, Karl Raimund, Sir, 1902---Congresses.
Rationalism--Congresses.
Social sciences--Philosophy--Congresses.