Helen L. Van Hoozer [and others]
Appleton Century Crofts, 1987
Buku Teks SO
Ur, Penny
Cambridge University Press, 2006
Buku Teks
Ur, Penny
Cambridge University Press, 1999
Buku Teks SO
edited by Linda Gask, Bulent Coskun and David A. Baron
Wiley-Blackwell, 2011
Buku Teks SO
Webb, Jon
Facet Publishing, 2005
Buku Teks SO