* [Learning about Dependency Injection and PHP](http://ralphschindler.com/2011/05/18/learning-about-dependency-injection-and-php) * [What is Dependency Injection?](http://fabien.potencier.org/article/11/what-is-dependency-injection) * [Dependency Injection: An analogy](https://mwop.net/blog/260-Dependency-Injection-An-analogy.html) * [Dependency Injection: Huh?](http://net.tutsplus.com/tutorials/php/dependency-injection-huh/) * [Dependency Injection as a tool for testing](http://philipobenito.github.io/dependency-injection-as-a-tool-for-testing/)