Tomasson, Richard F., author
Random Home, 1970
Buku Teks
Wicks, Rollo E.
N.Y. State Univ. of New York , 1958
Buku Teks
McClelland, David Clarence, author
Vakils, Feffer and Simon Private, 1961
Buku Teks
Luard, Evan, author
Macmillan, 1990
Buku Teks
Tinker, Anthea, author
Longman , 1984
Buku Teks