edited by Susan E. Israel, Gerald G. Duffy
Routledge, 2009
Buku Referensi
Sholapurkar, Amar A., author
Jaypee Brothers Pvt. Ltd., 2011
Buku Teks
Abbas Tashakkori, Charles Teddlie
SAGE Publications, 2010
Buku Teks
edited by Adolfo Paolini
Edward Elgar Publishing, 2016
Buku Teks
editor, Harry Helms [and others]
McGraw-Hill, 1983
Buku Referensi