I own some of the great books of orchestration, say, those by Pistons, Adler and Forsyth, but this book certainly is the best of the best. This is not a book about instrumentation (general information as range, articulations, characteristics, notation), rather it concentrates aspects such as resonance, register, doublings, combination of instrumental colors, as well as information about the chorus. These are the points that need to be considered in the course of orchestration. A well-organized book, with many orchestral excerpts drawn from Korsakov's own works. It is very useful for any orchestrators to understand the principles the author said.