Solid for packages

• http://butunclebob.com/ArticleS.UncleBob.PrinciplesOfOod

• https://adriancitu.com/tag/the-common-reuse-principle/

• https://en.wikipedia.org/wiki/Package_principles

• https://drive.google.com/file/d/0BwhCYaYDn8EgOGM2ZGFhNmYtNmE4ZS00OGY5LWFkZTYtMjE0ZGNjODQ0MjEx/view