Gordon, Robert Aaron, author
Columbia University Press, 1959
Buku Teks
editor, Burton R. Clark
Pergamon Press, 1992
Buku Referensi
Barnett, Ronald, author
Open University Press, 1994
Buku Teks
John C. Smart
Springer, 2012
eBooks
Burton R. Clark, Guy R. Neave, editors-in-chief
Pergamon Press, 1992
Buku Referensi