Bruhn, John G.
Charles C. Thomas Publisher, 1993
Buku Teks
Marry A. Nies, Melanie McEwen
Elsevier Saunders, 2011
Buku Teks
Northouse, Peter G., author
Prentice-Hall, 1985
Buku Referensi
Engelkirk, Paul G., author
Lippincott Williams & Wilkins, 2015
Buku Teks
Moini, Jahangir, author
Jones & Bartlett Learning , 2012
Buku Teks