Feiring, Bruce R.
Sage University Paper, 1986
Buku Teks
Thie, Paul R.
John Wiley & Sons, 1979
Buku Teks
Campbell, Hugh G.
Prentice-Hall, 1977
Buku Teks SO
Djati Kerami
Universitas Terbuka, 2008
Buku Teks
Hadley, George, 1930-
Addison-Wesley, 1962
Buku Teks