Gray, Richard, 1944-
Longman, 1991
Buku Teks
Bogan, Louise
Henry Regnery, 1951
Buku Teks
Dembo, L.S.
University of California Press, 1966
Buku Teks
Stepanchev, Stephen
Harper and Row, 1965
Buku Teks
Forrest-Thomson, Veronica
Manchester University Press, 1978
Buku Teks