- http://aurelio.net/er/
- http://guia-er.sourceforge.net/
- http://www.newmediacampaigns.com/page/regular-expression-tutorialhttp://www.newmediacampaigns.com/….
- http://gethifi.com/regexp/
- http://books.google.com.br/books?id=ucwR4KIvExMC
- http://regexlib.com/
- https://regex101.com/
- https://github.com/aloisdg/awesome-regex
- YouTube DRR9fOXkfRE⇓ ⇗
- Ruby