Maybe some folks pass on this book because they figure that since it was written so long ago, the info in it must be dated & thus not useful. That would be a mistake because while some of the info is outdated (particularly the tackle info), it's packed with so much info, methods, & techniques that still work, making this a great resource for any trout angler. It would be a shame to pass on this book.
Originally published in 1938, "Trout" was revised in 1952 & a lot more material was added - 25% more. With that added material there isn't an aspect of trout fishing that isn't covered between the covers, including spin cast fishing. There are chapter on wet flies, nymphs, streamers, dry flies, spin fishing - including chapters on the methods of using each. There are also chapters about different fishing conditions, lake fishing, & fly tying.
"Trout" is an extremely well written book. Bergman's writing style makes the book easy to read & the information easily understood. I'd like to say that this is not a technical text-book type of book, but it is - it's just that reading it is as if your good fishing buddy is reading it to you in their own words. So while "Trout" covers some very technical stuff, Bergman's down to earth writing style makes the book fun to read.
To my knowledge there is no other angling book that is as complete or as pleasurable to read as "Trout". Often referred to simply as "the Bergman book", many anglers have used it as a resource for decades. If you can think of it, it's covered in this book.
If you haven't read this book, do yourself a favor & do so. The info in it will make you a better trout angler. If you don't own a copy of it, make sure "Trout" is your next angling book purchase. There's a good reason it's been so popular with anglers for over seven decades.