edited by Christopher Nash
Routledge, 1990
Buku Teks
Duffus, C.M.
John Wiley & Sons, 1980
Buku Teks
Paul F. Lazarsfeld ... [and others]
Basic Books, 1967
Buku Teks SO
Greene, Ellin
Libraries Unlimited, 1996
Buku Teks
Sheldon, Lee H.
Course Technology, 2004
Buku Teks