London : Hamish Hamilton Ltd
Majalah, Jurnal, Buletin
Artikel Jurnal
Wardlaw, Gordon M., 1912-1989, author
McGraw-Hill, 2004
Buku Teks
edited by S. Venugopal Rao
Vikas Pub. House, 1988
Buku Teks
Rosenberg, Nathan, author
Cambridge University Press, 1976
Buku Teks