Tischler, Henry L.
Holt Rinehart and Winston, 1986
Buku Teks
Toennies, Ferdinand
The University of Chicago Press, 1971
Buku Teks
Andersen, Margaret L., author
Thomson, Wadsworth, 2009
Buku Teks
Hughes, Michael, author
McGraw-Hill, Higher Education, 2009
Buku Teks
Brinkerhoff, David B., author
Wadsworth, Cengage Learning, 2014
Buku Teks