(Robert Cecil Martin also known as Uncle Bob Martin - SOLID)[http://www.cleancoder.com/products]
(Summary of 'Clean code' by Robert C. Martin)[https://gist.github.com/wojteklu/73c6914cc446146b8b533c0988cf8d29]
Clean Code PDF: https://www.investigatii.md/uploads/resurse/Clean_Code.pdf
Clean Code Java: https://github.com/leonardolemie/clean-code-java
SOLID Java Examples: https://www.baeldung.com/solid-principles