After reading this book, I feel like I have a complete understanding of sharpening. The science, the applications, the range of equipment needed and, most importantly, when and how to let the professionals do the sharpening. (Referring to scissors or products which have option to be sharpened by the company as part of a lifetime warranty.)
This is a decent reference, but I think my dad has a better book with important info this one may not have... I am not sure, but I did not see the necessary pictures of the angles in this book.