Doris, Lillian
Prentice-Hall, 1960
Buku Teks
Becker, Esther R., author
Harper & Row, 1971
Buku Referensi
prepared under the editorial supervision of In Plain English, Inc.
Macmillan, 1996
Buku Referensi
Bredow, Miriam, author
Gregg Publishing, 1959
Buku Referensi
De Vries, Mary Ann, author
Prentice-Hall, 1991
Buku Referensi