Carrol, John
Harvard University Press , 1953
Buku Teks
Carroll, John B.
Harvad University Press, 1953
Buku Referensi
Andresen, Tetel Julie, author
Routledge, 1990
Buku Teks
Dewhurst, J. Frederic, author
Twentieth Century Fund, 1955
Buku Teks
Head, Sydney W., author
Houghton Miffiln, 1972
Buku Teks