Coombs, Philip H.
Rajawali, 1984
Buku Teks
Coombs, Philip H.
Johns Hopkins University Press, 1974
Buku Teks
Coombs, Philip H.
John Hopkins University Press, 1988
Buku Teks
King, Kenneth
Longmann Group, 1991
Buku Teks
edited by Keith Watson
Croom Helm, 1982
Buku Teks