United Nations Educational, Scientific and Cultural Organization, 1977
Buku Teks
Newman, David M., author
McGraw-Hill , 2012
Buku Teks
Blalock, Hubert M., author
Prentice-Hall, 1982
Buku Teks
Loomis, Charles P., author
Prentice-Hall, 1957
Buku Teks
Sztompka, Piotr, author
Prenada, 2011
Buku Teks