Sergey Kasparov's Doubled Pawns: A Practical Guide isn't the sort of book most of us would sit down with and go through page by page, but it can be useful as a reference work. Think of it as a sort of encyclopedia rather than a novel, and you'll have the right idea.
You might wonder why anyone would write a book about doubled pawns, and here I'll refer you to the last paragraph. There isn't some essence of doubled pawn positions that covers them all, some key, principle, or secret such that if you possess it, you'll understand how to play any and all positions with doubled pawns. That model won't work, and doesn't exist.
What Kasparov does instead is to look at this sort of doubled pawn position and that, doubled pawns in opening x and opening y. In that context, the book makes sense, and becomes useful to those who play on either side of the opening in question.
The book comprises 148 games distributed through 10 chapters, some devoted to specific openings and some not, though many of the non-specific chapters still cluster around a limited number of openings.
Chapter 1 covers doubled pawns arising after ...g7xf6, which arises, for example, in the Bronstein-Larsen Variation of the Caro-Kann and in various Sicilians (e.g. the Richter-Rauzer line of the Classical).
Chapter 2 covers structures resulting after hxg and axb, which often arises in the Caro-Kann and the Slav.
Chapter 3 is on doubled pawns in the middle of the board. The first examples come from the line 1.e4 d6 2.d4 Nf6 3.Nc3 e5 4.dxe5 dxe5 5.Qxd8+ Kxd8 6.Bc4 Be6 7.Bxe6 fxe6, and diversifies into other openings, such as Italian-like Ruys where Black plays ...Be6, White takes with the bishop and Black recaptures with the f-pawn.
Chapter 4 is on isolated doubled pawns (which could have included the doubled pawns in the Pirc-Philidor line mentioned in the previous paragraph). Several variations are covered, and the focus at the end is on the Short Variation in the QGD that came on hard times with the Carlsen-Kramnik game from the 2016 Norway Chess tournament (1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.cxd5 exd5 5.Bg5 c6 6.e3 Bf5 7.Qf3 Bg6 8.Bxf6 Qxf6 9.Qxf6 gxf6 etc.).
Chapter 5, "Spanish" Formations, would have been better entitled "Doubled Pawns in the Exchange Ruy", as all the examples come from that variation. He looks at a variety of Black's conceptual options, so if you play either side of the variation you're likely to find this chapter especially valuable.
Chapter 6 looks at a grab bag of captures away from the center - often exf3 or ...exf6 as in the 4...Nf6 5.Nxf6+ exf6 line of the Classical Caro-Kann.
Chapter 7 concerns itself with doubled pawns on the c-file - think of Nimzo-Indian lines with ...Bxc3(+) bxc3 as your template.
Chapter 8 is a long one on Rossolimo structures, with long sections on both ...dxc6 lines and those with ...bxc6. (There are further distinctions as well, but the big divide is between ...bxc6 and ...dxc6 structures.
Chapter 9 looks at the doubled pawn structure arising in the current main line of the Petroff: 1.e4 e5 2.Nf3 Nf6 3.Nxe5 d6 4.Nf3 Nxe4 5.Nc3 Nxc3 6.dxc3.
Chapter 10 rounds off the book, and is a grab bag of other ideas that don't fit in other chapters and are too short for their own chapters. There are sections on doubled f6/f7 pawns in Sicilian/Sicilian-like endings, doubled pawns in the Benoni, tripled pawns, doubled pawns in the Berlin, doubled pawns on the e-file (not like the ones in chapter 3), French structures, doubled pawns with opposite-colored bishops, and to close things a miscellany within the potpourri of the chapter.
The book is most attractive as a reference book, and trainers especially might pick it up for that reason.