Book: https://www.amazon.com/Refactoring-Improving-Design-Existing-Code/dp/0201485672/ref=sr_1_4?crid=BV69TL08DNLF&keywords=refactoring&qid=1679863070&s=books&sprefix=refactoring%2Cstripbooks%2C151&sr=1-4&ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840