Towle, Joseph W., author
Houghton Miffiln, 1965
Buku Teks
Nicholson, T.A.J., author
Macmillan, 1978
Buku Teks
Veech, Annette M., author
Prentice-Hall, 2002
Buku Teks
Ziegler, Raymond J.
John Wiley & Sons, 1962
Buku Teks
Champion, Dean J., author
McGraw-Hill, 1975
Buku Teks