Columbia subject headings:
Philosophers--Biography--Dictionaries.
Philosophy, Modern--20th century--Bio-bibliography.
Philosophy, Modern--20th century--Dictionaries.
Philosophy--History.
Harvard subject headings:
Philosophers--Biography--Dictionaries.
Philosophy, Modern--20th century--Bio-bibliography.
Philosophy, Modern--20th century--Dictionaries.
Princeton subject headings:
Philosophers--Biography--Dictionaries.
Philosophy, Modern--20th century--Bio-bibliography.
Philosophy, Modern--20th century--Dictionaries.
Philosophy--History.