Surbakti, Ramlan, author
Ministry of Home Affairs R.I., 2000
Buku Teks
Heady, Ferrel, author
Prentice-Hall, 1966
Buku Teks
Heady, Ferrel, author
Marcel Dekker, 1991
Buku Teks
edited by Samuel J. Bernstein
Pergamon Press, 1976
Buku Teks
Wakefield, Jill, author
Kluwer, 2007
Buku Teks