Crabbe, Ernest H.
South-Western Publishing, 1961
Buku Teks
Lincoln, Edmond E.
McGraw-Hill, 1941
Buku Teks
Conover, Hobart H.
Allyn and Bacon, 1977
Buku Teks
Griffin, Ricky W.
Pearson Education International, 2006
Buku Teks
Griffin, Ricky W.
Prentice-Hall, 1999
Buku Teks