Adams, J. Alan
McGraw-Hill, c1973
Buku Teks
Gerstner, Merrill H.
Amacom, 1974
Buku Teks SO
Berman, Howard J.
University of Michigan Press, 1982
Buku Teks
Rolph, Earl R.
Ronald Press, 1961
Buku Teks
Singh, U.K.
New Delhi : Anmol Publications, 1998,
Buku Referensi