Classic philosophical questions
editor, James A. Gould
Charles E. Merrill , 1971
 Buku Teks
Classic philosophical questions
edited by James A. Gould
Merril Publishing, 1989
 Buku Referensi
Barnes, Winston H.F.
The philosophical predicament
Adam & Charles Black, 1950
 Buku Teks
Langer, Susanne K.
Philosophical sketches
John Hopkins Press, 1964
 Buku Teks
Ayer, Alfred Jules, 1910-1989
The central questions of philosophy
Penguin Books, 1982
 Buku Teks