I am an industry professional who bought this book to be a small, handy pocket reference, and I am pretty disappointed with what it contains for the price. It's basically just a small formula book with very little explanation for each section. The pages are literally not large enough for anything meaningful to fit on them, and the text is often times far too specific to one application. I would recommend this book if it cost $5, but for $50, you can do much, much better.