Carlson, Rick
The Mosby , 1987
Buku Teks
Cherry, Barbara
Elsevier , 2011
Buku Teks
edited by Ng Chee Yuen, Charla Griffy-Brown
International Development Research Institute, 2000
Buku Referensi
Cherry, Barbara
Elsevier Mosby, 2011
Buku Teks
Ng Chee Yuen, Charla Griffy-Brown
International Development Research Institute , 2001
Buku Teks