Ethridge, Marcus E., author
Wadsworth, 2010
Buku Teks
Lipson, Leslie, author
Prentice-Hall, 1954
Buku Teks
Ranney, Austin, author
Holt, Rinehart and Winston , 1958
Buku Teks
Davies, Ioan
Pall Mall Press, 1970
Buku Teks
Mackenzie, W.J.M
Penguin books, 1978
Buku Teks