I like to do research before buying a book. But here's a list of must haves in no particular order:
- Dvoretsky's School of Chess Excellence volumes
- Dvoretsky's Endgame Manual
- Karpov's Best Games by Karpov
- Fischer's My 60 Memorable Games
- Smyslov's 2 volume set
- Botvinnik's first two volumes (third optional, first two still have plenty of Botvinnik games)
- Zurich 1953 by Najdorf (beware some atrocious typos in notation)
- Alekhine's Best Games (Russell Enterprises version)
- Aagard's GM Prep series
- Secrets of Pawn Endings
- Fundamental Chess Endings
- Endgame Strategy
- Secrets of Chess Endgame Strategy
- How to Play Chess Endgames
- Dynamic Pawn Play
- Pawn Structure Chess
- New Art of Defence in Chess
- Practical Chess Defence
- How to Defend in Chess
- Art of Attack in Chess
- My System
- Chess Praxis
- Soviet Middlegame Technique
- Questions of Modern Chess Theory
- Masters of the Chessboard
- Modern Ideas in Chess
- San Luis 2005
- Nunn's Chess Endings 3 volume set (Understanding Chess Endings then volume 1 and 2)
Averbakh's 5 volume set (especially queen endings and minor piece ending volumes because most specific piece ending books focus on either rook endings or pawn endings) is great to set up positions in a computer to draw or defeat it from.
I used to have 132 books. I gavet 104 away here a lot of them were in discriptive notation.
Here is the list of the books I gave away.
http://www.chess.com/forum/view/chess-equipment/this-is-the-list-of-book-im-giving-free-to-the-member-that-paid-the-freight
I only kept a few and now I only have 10.