edited by G. N. Appell and Leigh R. Wright
Cornell University, 1978
Buku Referensi
Payne, James L., author
Lytton, 1975
Buku Teks
Impex India, 1967
Buku Teks
Reynolds, Paul Davidson, author
Prentice-Hall, 1982
Buku Teks
Knight, Peter T., author
Sage, 2002
Buku Teks