GNU Aspell is a Free and Open Source spell checker designed to eventually replace Ispell. It can either be used as a library or as an independent spell checker.
J. In, S. Shirani, and F. Kossentini. Acoustics, Speech and Signal Processing, 1998. Proceedings of the 1998 IEEE International Conference on, 5, page 2633-2636. (1998)
T. Strutz. 4th International ITG Conference on Source and Channel Coding, (2002)source code available from http://www.embl-hamburg.de/~tilo/Software/CoBALP.tar.gz.