Without further ado, I would like to recommend one book and its brochure.
"Refactoring. Improving the design of existing code" Martin Fowler A book about how to edit your own and other people's code so that subsequent changes to it and adding new functionality bring less pain and less time, making the code easier to read. The examples in the book are presented in Java.
Java Code Conventions Brochure Recommendations for code formatting, variable naming, spacing, etc. Also improves code readability. PDF (maybe also available in Russian)
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