Dubelaar, C.N.
Foris Publications, 1986
Buku Teks
Frideres, James S.
Prentice Hall Canada, 1988
Buku Teks
Hibben, Frank C.
Hill and Wang, 1960
Buku Teks
edited by Joanna Overing, Alan Passes
Routledge , 2000
Buku Teks
Cooke, David C.
A Popular Library Eagle Book, 1955
Buku Teks