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LINKS:

http://citeseerx.ist.psu.edu/

http://en.wikipedia.org/wiki/Regular_expression
http://en.wikipedia.org/wiki/Regular_expression#POSIX_Extended_Regular_Expressions
http://en.wikipedia.org/wiki/Basic_regular_expression#POSIX_Basic_Regular_Expressions
http://en.wikipedia.org/wiki/Regular_language
http://en.wikipedia.org/wiki/Finite-state_machine
http://en.wikipedia.org/wiki/Nondeterministic_finite_state_machine
http://en.wikipedia.org/wiki/Deterministic_finite-state_machine
http://en.wikipedia.org/wiki/Awk
http://en.wikipedia.org/wiki/Sed
http://en.wikipedia.org/wiki/Grep
http://swtch.com/~rsc/regexp/regexp1.html
http://swtch.com/~rsc/regexp/regexp2.html
http://swtch.com/~rsc/regexp/regexp3.html
http://freshmeat.net/projects/tre/
http://code.google.com/p/re2/
http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html#tag_09_04
http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap09.html#tag_09_03
http://en.wikipedia.org/wiki/Moore_machine
http://en.wikipedia.org/wiki/Mealy_machine
http://en.wikipedia.org/wiki/Finite_state_transducer
http://en.wikipedia.org/wiki/Pattern_matching
http://en.wikipedia.org/wiki/Perl_Compatible_Regular_Expressions
http://www.regular-expressions.info/
http://www.regular-expressions.info/brackets.html
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.103.9231
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1.4400
http://citeseerx.ist.psu.edu/search?q=finite+state+transducer&submit=Search&sort=rel

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BOOKS:
http://www.cs.colorado.edu/~martin/slp.html

Extended Finite State Models of Language
  In the series  Studies in Natural Language Processing,
  Cambridge University Press, 1999, ISBN 0-521-63198-X,
  hardbound, x+278 pages.