Wilkinson, Edward J., author
Wolters Kluwer Health, 2012
Buku Teks
Rossi, Renzo, author
Macmillan, 1996
Buku Referensi
Dixon, D. F.
Longman Cheshire , 1982
Buku Teks
McGraw-hill Open Univ. press , 2006
Buku Teks
Wilkinson, Caroline
Cambrigde University Press , 2008
Buku Teks