Collins, Harry, author
Cambridge University Press , 1993
Buku Teks
Kishore, Swapna, author
Tata McGraw-Hill, 1991
Buku Teks
Lambert, A. Vickie, author
Prentice Hall Englewood Cliffts , 1985
Buku Teks
Putnam, Mabel Raef
Charles Scribner's, 1954
Buku Teks
Hofsoos, Emil
Gulf Publishing Company, 1970
Buku Teks