Here are some useful links that will help you during the onboarding, but will also prove useful later on.
These are some of really useful books to read, and are located at the Infinum Library usually in digital format. You can browse the library and find other useful books to read, these are some of the recommendations that we believe will help you become a better developer:
Robert C. Martin - Clean Code: A Handbook of Agile Software Craftsmanship
Robert C. Martin - The Clean Coder: A Code of Conduct for Professional Programmers
Robert C. Martin - Clean Agile: Back to Basics
Martin Fowler - Refactoring: Improving the Design of Existing Code