useful books: get the best pdfs for free

Refactoring:

Martin Fowler: "Refatoring"
https://www.csie.ntu.edu.tw/~r95004/Refactoring_improving_the_design_of_existing_code.pdf

Robert C Martin

• Architecture – The Lost Years (Robert C. Martin)
• Agile Software Development (Robert C. Martin)
• The Clean Coder (Robert C. Martin)
• Clean Code (Robert C. Martin)
• www.cleancoders.com (Robert C. Martin)