Hans-Joachim. Mittag & Horst Rinne 
Statistical Methods of Quality Assurance [PDF ebook] 

This comprehensive textbook is a basic reference which should be recommended to students and teachers in engineering, technology and management as well as to the whole community of professionals already working in quality-related areas.
The book aims to be a step-by-step introduction to statistical quality assurance. It has been specifically designed for self-study and includes over 100 fully solved exercises and worked examples. In addition to traditional quality control procedures the book also presents very carefully elaborated results of recent research in order to encourage their adoption into practice.