Balmer, L.
Pitman, 1970
Buku Teks
Rees, W. G., author
Cambridge University Press, 1994
eBooks
Childs, Peter R.N., author
Butterworth-Heinemann, 2014
eBooks
Pierce, Conway, author
W H Freeman, 1965
Buku Teks
Hammond, W. Rogers (William Rogers), 1920-1990, author
Prentice-Hall, 1961
Buku Teks