Refactoring is an excellent book written by Martin Fowler. He recently released a second edition. I'm reading it now and can recommend it to anyone interested in writing better code. Here's an interview with the author on the second edition of the book.
InfoQ interviewed Fowler about the major changes in the 2nd edition of Refactoring, how to recognize code smells and refactor code, how code reviews and refactoring support each other, what tech leads can do to encourage refactoring, the benefits refactoring brings, using tools for refactoring, and mob programming.