Longley, Dennis, author
Macmillan, 1982
Buku Referensi
Gordon, Michael, author
Kogan Page, 1986
Buku Referensi
Freedman, Alan, author
Amacom, 1995
Buku Referensi
Elsevier Scientific Publishing, 1971
Buku Referensi
editor-in-chief, Sybil P. Parker
McGraw-Hill, 1987
Buku Referensi