Eyestone, Robert
John Wiley & Sons, 1978
Buku Teks
Currie, Elliott, author
Little, Brown, 1984
Buku Teks
edited by Grace J. Kelleher
John Wiley & Sons, 1970
Buku Teks
Dinitto, Diana M., author
Pearson, 2012
Buku Teks
Sorokin, Pitirim A.
The Free Press, 1959
Buku Teks