Dauer, Victor P., author
Burgess Publishing, 1975
Buku Teks
Lewer, Helen, author
Macmillan, 1983
Buku Teks
Gallahue, David L., author
McGraw-Hill, 2012
Buku Teks
Kay E. Sanders and Alison Wishard Guerra, editors
Oxford University Press, 2016
eBooks
Riehl, C. Luise, author
Chas A bennet , 1966
Buku Teks