Hales, T. B.
Ellis Horwood, 1990
Buku Teks
Turner, William C., author
Robert E. Kreiger , 1980
Buku Referensi
Rita Rogayah, author
Fakultas Kesehatan Masyarakat Universitas Indonesia, 2014
UI - Tesis (Membership)
by Collin J. Watson [and others]
Allyn and Bacon, 1993
Buku Teks
Heady, Earl O., author
Prentice-Hall, 1954
Buku Teks