SourceMaking — is the best information source on the Web on such software development topics as design patterns, refactoring and UML. A lot of information freely available through the site's pages, so feel free to use bookmarklet to leave interesting chapters for further reading.
Y. Eshel, O. Levi, H. Roitman, and A. Nus. Proceedings of the 44th International ACM SIGIR Conference on Research and Development in Information Retrieval, ACM, (July 2021)