Successful software requires constant modifications. To guarantee the continuous proper functioning of the applications, developers need to understand them well, particularly by having an accurate map of the dependencies between the parts they are modifying. However, some of these dependencies are not easily identified. For example, in an Android application, there are dependencies between the Java source code and XML parts, some of which are materialized by a generated "R" Java class. We call such dependencies external because they are introduced by some agent external to the source code. On top of the categorization of dependencies defined in the literature, we define restrictions on the External Dependencies that allow us to verify the source code and identify possible flaws. We created a common approach relying on reusable patterns to search for containers and entities that are part of such dependencies and implemented it in a prototype that we validate on two different projects from GitHub and developed using different frameworks.