Bach, George Leland, author
Prentice Hall of India, 1977
Buku Teks
Weimer, David L., author
Prentice-Hall, 1992
Buku Teks
Bach, George Leland, author
Prentice-Hall, 1966
Buku Teks
by Sidney S. Alexander ... [et.al]
Brookings Institution, 1959
Buku Teks
Hansen, Alvin Harvey, 1887-1975, author
Amacom, 1977
Buku Teks