Can anyone recommend a positional book focused on preparing pawn breaks? Feel free to share more than one book. I'm very interested in understanding better those preparatory moves.
@Marcelo, it really depends on what you mean by "preparing". 

If you mean that VERY specifically "what specific moves" in every case, that is too general, and there are no such books. If you mean that as "how do I play for a pawn break", in general, then you are really just asking about pawn play, and pawn structures.

Here is a fairly complete list of books about opening pawn structures and pawn play, in general.


"Chess Structures: A Grandmaster Guide" by GM Mauricio Flores Rios is the single best book on OPENING pawn structures currently out there, but it misses some.
"Pawn Structure Chess" by GM Andy Soltis is VERY weak in the analysis, but the general ideas still hold up.
"The Ideas Behind the Chess Openings, Algebraic Edition" by GM Reuben Fine
"Chess Opening Essentials" by New in Chess Four Volumes cover every opening, but each one is done fairly lightly, so this is a true beginner's guide.


Here is a list of books on general pawn play. 


“Complete Chess Strategy” volumes 1,2 and 3 by Ludek Pachman. (This teaches about many basic plans, and what you are striving for with your pieces and pawns, especially. This made a light go off in my head, and THIS is what made me a master.)
"Winning Pawn Structures" by GM Alexander Baburin
"Understanding Pawn Play" in Chess by GM Drazen Marovic
"Dynamic Pawn Play in Chess" by GM Drazen Marovic
"Winning Chess Middlegames: An Essential Guide to Pawn Structure" by GM Ivan Sokolov
"Chess Middlegame Strategies Volume 2" by GM Ivan Sokolov
"The Power of Pawns: Chess Structure Fundamentals for Post-beginners" by GM Jörg Hickl
"Isolani Strategy: Strengths and Weaknesses of the Isolated Queen's Pawn" by GMs Adrian Mikhalchishin, Alexander Beliavsky, Oleg Stetsko
"Understanding Maroczy Structures" by GMs Adrian Mikhalchishin and Georg Mohr
And the original book on the subject, but it uses some weird terms: "Pawn Power" by IM Hans Kmoch