1. Frost & Prechter's "The EW principle" - it's the Bible 2. The complete EW writings of Hamilton Bolton 3. Visual guide to EW trading by Wayne Gorman & Jeffrey Kennedy 4. EW principle applied to the FX markets by Robert Balan
5. EW trading by Jeffrey Kennedy 6. RN Elliott's masterworks 7. Mastering the EW principle by Constance Brown
From a practical perspective, the ones by Gorman/Kennedy & Balan are the gold standard. I have read each book many times n yet there is alws smth new each time.