ApiGen is the tool for creating professional API documentation from PHP source code, similar to discontinued phpDocumentor/phpDoc.

Sami: an API documentation generator

This manual describes the policy requirements for the Debian distribution.

phpDocumentor enables you to generate documentation from your PHP source code. This documentation provides an in-depth view of your project to you, your consumers and contributors.

The entire Pro Git book, written by Scott Chacon and published by Apress, is available here

This is a draft to bring automatic documentation to CSS files, like its known for JavaScript and PHP files through JavaDoc/DocTags.

CMSmatrix lets you easily compare the features in over 1200 content management system products. Check the boxes next to the software you're interested in and click the Compare button. CMS comparison data is added/maintained by the vendors who develop the products. If a product is out of date or not included in the matrix, be sure to contact the vendor of the software and ask them to update or add their product listing on CMSmatrix.org.