Aron, Elisabeth A., author
Lippincott Williams & Wilkins, 2002
Buku Teks
Stolte, Karen M., author
Lippincott, 1996
Buku Teks
McMurray, Anne, author
Harcourt Mosby, 1999
Buku Teks
United States. Department of Labor
Illinois : The United States Departemen of Labor, 1994, 1995
Buku Referensi
McMurray, Anne, author
Mosby , 2003
Buku Teks