Scarfe, Brian L., author
McGraw-Hill, 1977
Buku Teks
edited by Howard S. Elllis
Blakiston, 1949
Buku Teks
Spencer, Milton H., author
Worth, 1971
Buku Teks
Hicks, John, author
Oxford Univeristy Press , 1965
Buku Teks
edited by David Greenaway, Michael Bleaney, and Ian Stewart
Routledge, 1991
Buku Referensi