Tompkins, E. Berkeley
University of Pennsylvania Press, 1970
Buku Teks
Homo, Leon
Kegan Paul,Trench,Trubner & CO,LTD, 1927
Buku Teks
Manchester University Press, 1986
Buku Teks
Lowe, John, author
Routledge, 1994
Buku Teks
Fischer-Galati, Stephen A.
Harvard University Press, 1959
Buku Teks