Merriam-Webster's, Incorporated, 1993
Buku Referensi
Springfield, Massacuset : G.& C. Merriam Co., Publishers, 1948.
Buku Teks
Merriam-Webster, Inc., 1988
Buku Teks
Cornog, Mary Wood
Merriam-Webster Inc., 1994
Buku Referensi
Bolander, Donald O.
Lexicon Publication, 1993
Buku Referensi