NM Elijah Logozar's review on Amazon asks, "Who is the target audience?":
"In some ways, I get the impression that the author is writing as if this is your first tactics book, explaining the themes and basics. A lot of these puzzles are only a couple of moves long, and that's consistent with the idea of a tactics primer for beginners, although I really didn't get that impression for a lot of these. Is a beginners tactics book going to include numerous endgame studies that are 10-15+ moves long, and improvements on world champion games, with solutions sometimes extending 5-10 moves deep? (...)"
I have a similar issue with The Soviet Chess Primer by Ilya Maizelis, which I'm currently reading, and which Logozar also mentions in his review.
Key Elements of Chess Tactics and Key Elements of Chess Strategy are translations of a book by Georgy Lisitsin originally published in Russian in one volume ("Strategy and Tactics of Chess", 1950s). Apparently, it's one of those "legendary manuals in the Soviet chess school".
I had a brief look at the excerpt provided by Quality Chess and it's probably above my level. For the example positions at the start of chapter 2, I didn't find any of the solutions (at least beyond suspecting what the first move in Alatortsev – Goglidze on page 154 would be). For the six exercises on page 317, I found the solution only for positions 1 and 3.
My rating is just above 1200. I would be interested in the views of higher-rated players about the recommended rating band for this book.