Adam Ritcjie, Randall Thomas, editor
Taylor & Francis Group, 2009
Buku Teks
edited by Peter Roberts and Hugh Sykes
Sage, 2003
Buku Referensi
edited by Peter Roberts, Hugh Sykes
Sage Publications, 2003
Buku Referensi
Choldin, Harvey M.
McGraw-Hill, 1985
Buku Teks
McGraw-Hill, 2000
Buku Teks