Lemkau, Paul V.
McGraw-Hill Book Company, INC, 1955
Buku Teks
Barry, Patricia D.
Lippincott , 1998
Buku Teks
Sage Publications, 1987
Buku Teks
Peter Aggleton, Jane Hurry, Ian Warwick, editor
John Wiley & Sons, 2000
Buku Teks
Bernard, Harold W.
1970
Buku Teks