Garman, E. Thomas
Houghton Miffiln, 1985
Buku Teks
Kapoor, Jack R., 1937-
McGraw-Hill/Irwin, 2004
Buku Teks
Richards, R. Malcolm
Scott, Foresman, 1984
Buku Teks
Unger, Maurice A.
Allyn and Bacon, 1969
Buku Teks
Oxford University Press, 1993
Buku Referensi