Shafritz, Jay M., author
Wadsworth, 2016
Buku Teks
Hatch, Mary Jo
Oxford University Press, 1997
Buku Teks
Waldman, Don E., author
Pearson, 2007
Buku Teks
Tompkins, Jonathan R., author
Wadsworth, 2005
Buku Teks
Seckler-Hudson, Catheryn, author
Washington, D.C., The American University Press
Buku Teks