Moore, Frank Ledlie
Contemporary books, 1996
Buku Referensi
Heling, Bureau Menno
Het Spectrum, 1994
Buku Referensi
edited by Dagobert D. Runes and Harry G. Schrickel
Philosophical Library, 1946
Buku Referensi
Munsterberg, Hugo, 1916-1995
Charles E. Tuttle, 1957
Buku Teks
editor, John Prest
Oxford University Press, 1993
Buku Referensi