A great book to start 'The Mastering Engineer's Handbook'
If you are interested in the history of the Art of Mastering, do check out these articles..
http://www.dangerousmusic.com/learning-center/mastering
Also worth a visit, this blog:
All about producing and mastering audio for disc, the web and beyond http://mworksmastering.blogspot.fr/
If you want a test master, feel free to This email address is being protected from spambots. You need JavaScript enabled to view it. to us and we will send you a 30s sample.