Davidson, Paul
Edward Elgar, 2011
Buku Teks
Ferguson, C.E.
Duke University Press, 1964
Buku Teks
Branson, William H.
Harper & Row, 1979
Buku Teks
Leijonhufvud, Axel
London Oxford University Press , 1968
Buku Teks
McCandless, George T.
Prentice-Hall, 1991
Buku Teks