General Programming:
- A Philosophy of Software Design by John Ousterhout
- Clean Code: A Handbook of Agile Software Craftsmanship by Robert C. Martin
- Refactoring, 2nd Edition by Martin Fowler
- Working Effectively with Legacy Code by Michael Feathers
C#:
- CLR via C#, 4th Edition by Jeffrey Richter
- Concurrency in C# Cookbook by Stephen Cleary
- Dependency Injection by Mark Seemann
I will periodically update this list, when I will find new books that are worthy to be recommended.