ESOMAR, 1972
Buku Teks
Ozcan, Yasar A.
Jossey- Bass, 2009
Buku Teks
Spiegel, Allen D.
Ablex Publishing Corporation, 1991
Buku Referensi
Parikh, Ashok K.
Harvester Wheatsheaf, 1990
Buku Teks SO
Schulman, Lawrence S.
John Wiley & Sons, 1981
Buku Teks SO