Weber, Max, 1864-1920, author
Routledge & Kegan Paul, 1977
Buku Teks
Stenlund, Soren
Routledge, 1990
Buku Teks
Black, Max
Wilhelm Fink, 1973
Buku Teks
Robert M. Hutchins, Mortimer J. Adler, editors in chief
Encyclopaedia Britannica, Inc., 1963
Buku Referensi
George allen & Unwin, ltd, 1948
Buku Teks