This is my Middlegame Section (Advanced Players). Most of what I would need for IM or GM study is here.
Here's my top players who never-made-it-to-World Champion section. Some Fischer books are stashed here because of overflow from my World Champion section. Portisch, Korchnoi,Nezhmetsinov, Stein, Gligoric and Larsen, along with the old masters like Rubinstein, Tarrasch, Reti etc.
My Openings and Positional Play for 1200-2000 ELO section: These were my favourites when I was studying chess a lot. The opening books were kept to a minimal now, as I realised that they get outdated quite soon. So I chose mainly books that explain how to play the openings rather than the repertoire books (but of course, you need at least 1 good one for the openings you play).
My favourites were Improve Your Chess Now, Purdy, Improve your Chess Results by Zak (Spassky's trainer) and the book next to it - Study Chess with Tal (by Koblenz, Tal's trainer).
Forgot about my Tactics and Endgames...
Here's where I store my Russian Master's English translated books along with the Kasparov Series. Many are great but have gone sadly out of print.