Deloughery, Grace L.
Mosby, 1977
Buku Teks
Kelly, Lucie Young
Macmillan, 1981
Buku Teks
Karen Jensen
Sense, 2012
eBooks
Roberts, Norman, author
Library Association Publishing, 1991
Buku Teks
Nagel, christian, author
Wiley Publishing, inc., 2010
Buku Teks