Jackson, John H., author
St.Paul,Minn., 1995
Buku Teks
Sykes, Alan O.
St.Paul,Minn., 1995
Buku Teks
Jackson, John H., author
West Publishing, 2013
Buku Teks
edited by Frederick H. Hartman
McGraw-Hill, 1951
Buku Teks
edited by Andrew Gyorgy and Hubert S. Gibbs
Prentice-Hall, 1955
Buku Teks