Johnson, Miranda
Oxford University Press, 2016
eBooks
Kayleen M. Hazlehurst
Avebury, 2001
Buku Teks
Frideres, James S.
Prentice Hall Canada, 1988
Buku Teks
Fletcher, Sydney E.
Grosset & Dunlap, 1954
Buku Teks
Tomain, Joseph P.
West Publishing Company, 1981
Buku Teks