Morgan, Carl
Cheltenham, Ont., Boston Mills Press, 1977
Buku Teks
Lidz, Carol Schneider, author
John Wiley & Sons, 2003
Buku Teks
Levey, Michael
Penguin, 1967
Buku Teks
Smith, Robert T., 1918-1995, author
McGraw-Hill , 2007
Buku Teks
Gray, Basil
Buku Teks