Norman K. Denzin, Yvonna S. Lincoln, editors
Sage Publications, 2000
Buku Referensi
editor, Owen D.W. Hargie
Routledge, 1997
Buku Referensi
Collin, P. H., author
Peter Collin Publishing, 1997
Buku Referensi
Hampel, Clifford A.
Van Nostrand Reinhold, 1982
Buku Referensi
edited by John A. Adamovics
Marcel Dekker, 1997
Buku Referensi