Hagopain, Mark N.
Longman, 1978
Buku Teks
Macridis, Roy C., author
Little, Brown, 1983
Buku Teks
Hague, Rod., author
Palgrave Macmillan , 2013
Buku Teks
Curtis, Michael, author
Harper & Row, 1978
Buku Teks
by Carlton Clymer Rodee ... [et al.]
McGraw-Hill, 1983
Buku Teks