Kirn, Elaine
McGraw-Hill, 1990
Buku Teks
Allan, Dave
Oxford University Press, 1992
Buku Teks SO
Pavlik, Cheryl
[publisher not identified], [date of publication not identified]
Buku Teks
Blair, Walter
Scott Foresman, 1955
Buku Teks
Funk & Wagnalls, 1980
Buku Referensi