Step by Step guide to validate user name with PHP preg_match - DEV Community
Typing error in the documentation of the preg_match function (https://www. php.net/manual/fr/function.preg-match.php) · Issue #102 · php/doc-fr · GitHub
The unexpected dangers of preg_replace() - Bitquark
Tutorial PHP - Teil 15 - Reguläre Ausdrücke
regex works in all regex testers, not with php preg_match(), driving me insane - Stack Overflow