1. Juliet Test Suite.
http://samate.nist.gov/SRD/testsuite.php
2. PHP static code analysis tools list.
https://github.com/exakat/php-static-analysis-tools
3. CWE - Common Weakness Enumeration (2015).
http://cwe.mitre.org/
4. Exakat (2019).
https://www.exakat.io/
5. HTMLPurifier (2019).
http://htmlpurifier.org/