For technique I recommend...

1. Charlie Craven's Basic Fly Tying and his web site, simply the best detailed instructions I have ever found.

2. The Flytyer's Benchside Reference, big and expensive. Contains an amazing wealth of information, everyone needs this book. Step by step info on ALL the fly tying techniques ever developed since huans walked upright, or something pretty close to it.

For fly recipes, I would want...

3. Fly Patterns of the Umqua Feather Merchants, 1500 of the worlds best flies. This fine reference has a recipe and picture all the flies you would ever need, at least all the ones made by Upmqua!

I also like A.K. Best's 'Production Fly Tying Techniques' This book improved my fly quality and speed. Prehaps a good intermediate book for those that want to take it to the next level.