Christensen, Clayton M., author
Jossey-Bass Publishers, 2011
Buku Teks
Saran Kaur Gill, Nantana Gajaseni, editors
Universiti Kebangsaan Malaysia, 2012
Buku Teks
Barger, Christopher, author
McGraw-Hill, 2012
Buku Teks
Franck, Karen A., author
Wiley-Academy, 2000
Buku Teks
Artikel Jurnal