Bailey, Joe
Routledge & Kegan Paul, 1980
Buku Teks
Brym, Robert J., author
Wadsworth and Cengage Learning, 2013
Buku Teks
Ross, H. Laurence (Hugh Laurence), author
McGraw-Hill, 1973
Buku Teks
Jordan, Bill
Sage, 1998
Buku Teks
Weber, Max, 1864-1920, author
J.C.B. Mohr (Paul Siebeck) Tubingen, 1956
Buku Teks