One of the best books ever written on the subject of Self-Realisation/Liberation is the Seven Steps to Awakening, compiled by Michael Langford. It contains wonderful, clear and rare teachings for those who are able to truly take in what is presented here. If you are unfamiliar with these teachings you should definitely also read The Most Direct Means to Eternal Bliss which is perhaps a better introduction to the teachings.:

You can download the complete text of The Seven Steps to Awakening here