Keeble, Richard, author
Routledge, 2007
Buku Referensi
Abbot, Waldo
McGraw-Hill, 1957
Buku Teks
Bender, James F.
Thomas Y. Cornell, 1951
Buku Teks
edited by John T. Daugirdas, Peter G. Blake, Todd S. Ing.
Wolters Kluwer, 2001
Buku Referensi
Coulmas, Florian, author
Blackwell Publishers, 1998
Buku Teks