Black, Beth Perry, author
Missouri Elsevier/Saunders, 2017
Buku Teks
Seeeions, Laura Steibel, author
Prentice-Hall, 1982
Buku Teks
Bayles, Fred, author
CQ Press, 2012
Buku Teks
Beakley, George C
Macmillan, 1972
Buku Teks
Matthews, Janet R.
Allyn and Bacon, 1997
Buku Teks