Tong, Rosemarie Putnam
Westview press, 1997
Buku Teks
Kumarappa, J.C.
Bombay Vora & Co 1951
Buku Teks
Wanlass, Lawrence C., author
Appleton-Century-Crofts, 1953
Buku Teks
Taylor, A. E. (Alfred Edward), 1869-1945, author
Doubleday, 1952
Buku Teks
Heidegger, Martin, author
Harper & Row, 2001
Buku Teks