Hayes, Andrew F., author
The Guilford Press , 2013
Buku Teks
Ronny, author
Fakultas Matematika dan Ilmu Pengetahuan Alam Universitas Indonesia, 2007
UI - Skripsi (Membership)
editor, Michael S. Lewis-Beck
Sage Publications, Toppan Publishing, 1993
Buku Referensi
Lewis-Beck, Michael S., author
Sage, 1980
Buku Teks
McAdams, Alan K., author
Macmillan, 1970
Buku Teks