Knitting from the Top, by Barbara G. Walker:
As it says on the back of the book: The woman is a genius!
If you have any intentions of ever designing your own sweater (or pants for that matter!) you should have this book. If you hate to sew seams in your knitting, you should have this book. If you want to try on your garment as you go, you should have this book. If you want to knit something that will actually fit (with reservations for emotions after I have actually knitted something from the book), you should have this book.
In it, Barbara tells you exactly what you need to know to knit your own sweater, (or pants!) which ever style you like, for your measurements, with the yarn of you choice, from the top down. It is as simple as that, but that is not so simple. She goes through every eventuality, decreases, increases, collars, necklines, measurements, buttonholes and much, much more. This means that the book is text, a lot of text, there is a few diagrams here and there, but mostly page up and page down text. This is not a bad thing, all the text is necessary, it just means that if there is something you are wondering about, the answer is in there somewhere. I sat, and gladly read through a few of the patterns, just so I could really understand her way of working, and now, I cant wait to begin!
You should have this book.