Bayes, Nenna L., author
McGraw-Hill , 2012
Buku Teks
Jennings, Lucy Mae
Prentice-Hall, 1983
Buku Teks
prepared under the editorial supervision of In Plain English, Inc.
Macmillan, 1996
Buku Referensi
Dando, Sylvia, author
McGraw-Hill Book, 1987
Buku Referensi
Smith, Allen N.
South-Western Pub. Co, 1986
Buku Teks