Murphy, Raymond, author
McGraw-Hill , 1979
Buku Teks
Association for Educational and Training Technology; editor, C. W. Osborne
Kaogan Page, 1994
Buku Referensi
Rebentisch, Juliane, 1970-, author
Polity Press, 2016
Buku Teks
Raven, John
HK Lewis, 1977
Buku Teks
The Council for Research in Values and Philosophy, 2005
Buku Teks