Stenlund, Soren
Routledge, 1990
Buku Teks
edited by Ernest Sosa, Enrique Villanueva
Blackwell , 2006
Buku Teks
Katz, Jerrold J., author
George Allen and Unwin, 1972
Buku Teks
Grayling, A. C.
Blackwell Publishers, 1997
Buku Teks
Johnson, Alexender Sryan, author
Dover Publications, 1968
Buku Teks