Openings
The Ideas behind the Chess Openings by Reuben Fine
A classic but be sure to find a version in alegebraic (modern) notation.
Discovering Chess Openings by John Emms
Back to Basics by Carsen Hansten
Mastering the Chess Openings Volumes 1 to 4 by John Watson
Watson’s four volume series provides a comprehensive guide to the various opening systems and variations.
Middlegame and General
Chess Fundamentals by Jose Raoul Capablanca
Capablanca’s work, first published in 1921, covers all phases of the game and still regarded as a classic for new and intermediate players.
Understanding Chess Middlegames by John Nunn
This one covers important middlegame ideas and plans.
My System by Aron Nimzovitch
A classic and one of the best selling chess books since 1925. The positional ideas are fairly deep though, and it’s best to look at this as an improving player at 1500 Elo or higher.
Endgames
Chess Endings Essential Knowledge by Yuri Averbakh
Regarded as a classic, and covers all of the basic endgame ideas at a high level.
100 Chess Endgames you must know by Jesus de la Villa
Basic Chess Endgames by Reuben Fine
An in-depth survey of endgames, which can be used as reference work for the more advanced player.
Tactics
Chess Tactics by Paul Littlewood
Learn Chess Tactics by John Nunn
A systematic approach to different tactical ideas with lots of examples.
Game Collections
My 60 Memorable Games by Bobby Fischer
Fischer’s collection of his games with annotations. Still seen as the classic games collection.
Logical Chess Move by Move by Irving Chernev
Another classic. This is an excellent collection of GM games with an explanation of every move which should help you learn how to think at the board.