The other book is Alex Yermolinsky's Road to Chess Improvement. Mostly Yermolinsky believes in teaching by example. He presents his thoughts and then shows you how he applied them in his games. He's also one of the few authors who doesn't promise a magic answer to how to become a master. In fact, he admits he doesn't have all the answers and hard work, a lot of it, is going be required.
In one section of the book there is a heading The Number of Pawns is Just Another Positional Factor. Just prior to discussing this subject he wrote how early in his career he was a strong advocate of pure positional play and was a student of the games of Swedish GM Ulf Andersson who had a reputation as a very solid positional player, drawing a high percentage of his games and a great endgame player, especially Rook endings. Andersson was famous for winning seemingly unwinnable endgames and playing long, long games.
Eventually Yermolinsky realized that tactics were important, too, and nothing can substitute for tactical understanding and a tactical style is not, as viewed by some, inferior to a positional style. As he observed, the tactical style has the same right to exist as the positional approach.
In his early days his style dictated that risk had be diminished and ideally avoided because positional play should be enough to bring success. His losses were blamed on insufﬁcient technique. He did admit though that one benefit from studying Andersson's games was what he learned about endings paid off.
From 1981 to 1989, before he left the Soviet Union, he belonged to the Leningrad Army Sports Club chess team where he had the opportunity to study with GM Mark Tseitlin who taught him the value of the initiative. At first he viewed the initiative as a reward for a correctly chosen and properly implemented positional plan. That's when he was introduced to gambits. Note he wasn't talking about wild, crazy, unsound opening gambits that are so popular with authors today. He was talking about P-sacs where you give a little and get a little. When you sacrifice under those circumstances, you must be patient and shouldn’t expect immediate returns. He learned to treat a loss of a P as another positional factor that must be taken into the account, no more or less than any other positional factor.
In the following game, using one of my favorite openings, the Torre Attack, Yermolinsky discovered a P-sac in a routine position, seized the initiative and kept his opponent's K in the center and demonstrated that even then energetic play was called for. The result is a very instructive game.