Gavin Andrews, Mark Creamer, Rocco Crino, Caroline Hunt, Lisa Lampe, Andrew Page
Cambridge University Press, 2003
Buku Referensi
McFarland, Gertrude K., author
Mosby, 1989
Buku Teks
by Susan Martin Tucker ... [and others]
Mosby, 1992
Buku Teks
Ogilvie, Colin
Buuerworth-Heinemann, 1987
Buku Teks
Artikel Jurnal