Barber, James David
Prentice-Hall, 1977
Buku Teks
Parks, Lillian Rogers
Fleet Publishing , 1961
Buku Teks
Fersh, Seymour H., author
Public Affairs, 1961
Buku Teks
Sorensen, Theodore C., author
Columbia University Press, 1964
Buku Teks
editor, Susanne Wasum-Rainer, Ingo Winkelmann, Katrin Tiroch
Springer, 2012
eBooks