edited by Harry R. Warfel, Ralph Gabriel
American Book Company, 1963
Buku Teks
Ewing, David W., author
Free Press of Glencoe, 1964
Buku Teks
Ryle, Gilbert
Hutchinson's University Library, 1950
Buku Teks
Kim, Jaegwon, author
Westview Press, 2006
Buku Teks
Kenny, Anthony
Routledge, 1994
Buku Teks