edited by L. Andries van der Ark
Lawrence Erlbaum Associates, 2005
Buku Teks
Knoke, David, author
Thomson, 2002
Buku Teks
Erickson, Bonnie H., author
Open University Press, 1977
Buku Teks
Daniels, Michael J., author
Chapman & Hall / CRC, 2008
Buku Teks
Hinkle, Dennis E., author
Houghton Mifflin, 2003
Buku Teks