Williams, Norma
Tiger Books International, 1990
Buku Referensi
Carlson, Karen J.
Harvard Universiy press , 1996
Buku Teks
edited by Brenna H. Mayer
lippincott Willims & Wilkins, 2005
Buku Teks
Youngkin, Ellis Quinn
Appleton & Lange , 1998
Buku Teks
Medical Economics Data, 1994
Buku Teks