Whitten, D.G.A., 1921-
Penguin Books, 1972
Buku Referensi
Whitten, D.G.A., 1921-
Penguin Books, 1972
Buku Referensi
Bates, Robert L., editors
Anchor Books, 1984
Buku Referensi
Watt, Alec
Longman, 1982
Buku Referensi
edited by Sybil P. Parker
McGraw-Hill, 1997
Buku Referensi