Unit Testing:Principles, Practices and Patterns Paperback – Big Book, 16 March 2020

Unit Testing Principles, Practices, and Patterns: Effective testing styles, patterns, and reliable automation for unit testing, mocking, and integration testing with examples in C#

Refactoring: Improving the Design of Existing Code (2nd Edition) (Addison-Wesley Signature Series (Fowler))

Test Driven Development: By Example