Curzon, L. B., author
RREC, 1981
Buku Teks
Charmaz, Kathy, author
Sage , 2014
Buku Teks
Majors, Randall E., author
Prentice-Hall, 1997
Buku Teks
Mahzan Arshad, author
University of Indonesia, Faculty of Humanities, 2009
Artikel Jurnal
Colby, Diane S., author
Lange Medical, 1985
Buku Teks