Heimler, Charles H.
Charles E Merrill, 1977
Buku Teks
editor, J.H. Saurat
Karger, 1984
Buku Teks
Hoag, Erleen J.
Prentice-Hall, 1991
Buku Teks
Parson, Keneth H.
The University of Wisconsin Press, 1956
Buku Teks
Gerstner, Merrill H.
Amacom , 1974
Buku Teks