You will easily find some books with technical information for motor construction, although for a good theoretical foundation I would recommend reviewing the following texts:
Dear danilo, It is not clear what type of motor are you working on? The following book will give you a guideline for permanent magnet motor design, I recommend to focus specifically on a motor type to get better results.
Thus , I'm focusing on PMSM Brushless motors. In particulari 6slots / 4 poles motor type. If you have any other book about electrical motors (expecially PMSM) it could be really awesome!