Gilbert, Glen G., author
Jones and Burtlet, 2011
Buku Teks
CA Jossey-Bass, 2014
Buku Teks
Healey, Bernard J., author
Jones & Bartlett Learning, 2010
Buku Teks
Allender, Judith Ann, author
Wolters Kluwer, 2014
Buku Teks
Porterfield, John D.
Voice American Forum Lecture, [date of publication not identified]
Buku Teks