Spencer, Donald D.
Camelot Publishing Company, 1993
Buku Referensi
editor-in-chief, Sybil P. Parker
McGraw-Hill, 1987
Buku Referensi
Merriam-Webster, 2004
Buku Referensi
Vega, Connie de la, author
Edward Elgar, 2013
Buku Referensi
Vega, Connie de la, author
Edward Elgar Publishing, 2013
Buku Referensi