G. & C. Merriam, 1943
Buku Referensi
Springfield, Massacuset : G.& C. Merriam Co., Publishers, 1948.
Buku Teks
Merriam Webster, 1995
Buku Referensi
edited by Coleen K. Withgott, Austin G. Anderson
Merriam-Webster, 1981
Buku Referensi
Lexicon Publication, 1993
Buku Referensi