Manus-Hannaford, R.G.
Macdonald, 1964
Buku Teks
Fernald, Charles H.
Prentice-Hall, 1959
Buku Teks
Jenks, Ernest E.
Alexander hamilton Institute, 1962
Buku Teks
Kirkpatrick, Charles A.
South-Western Publishing, 1976
Buku Teks
Baduara S, Satar
Akademika Pressindo, 1984
Buku Teks