Refactory and Design Patterns: https://refactoring.guru
UML tutorial by Creately: https://creately.com/diagram-type/usage/choosing-right-uml-diagram
UML intro: http://www.cs.utsa.edu/~cs3443/uml/uml.html
UML cheat sheet by Lou Franco: https://loufranco.com/wp-content/uploads/2012/11/cheatsheet.pdf
Signal & slots by reference: https://www.embeddeduse.com/2013/06/29/copied-or-not-copied-arguments-signals-slots/
Overloading virtual functions in base class (Be careful!): Programming, Algorithm and Technical Tips: Can Virtual Functions Be Overloaded? (robentan.blogspot.com)
Static in C++ : https://www.bogotobogo.com/cplusplus/statics.php
Export/Import package: Simple Modern CMake Tutorial and example | Level Up Coding (gitconnected.com)