Probably the best book I’ve ever read in terms of an instructional or manual. 90% of the principles outlined in this book are still relevant in modern boxing, and Haislet outlines everything clearly, with relevant sources when required.
Reading this and Jack Dempseys book “Championship Fighting” are a great introduction to boxing fundamentals.
Originally published in 1940, this is the best book of it's kind I've been able find from the era. Much of what is shown is solid technique application that still is applicable to today. That said, some of his advice is outmoded, quaint, or rooted in gym myth. Contrasted to earlier books, it is a good book to show the evolution of boxing.