Reference 1: Bernhardt Wuensch. 3.60 Symmetry, Structure, and Tensor Properties of Materials, Fall 2005. (Massachusetts Institute of Technology: MIT OpenCourseWare), http://ocw.mit.edu (Accessed 4 Feb, 2015). License: Creative Commons BY-NC-SA
Reference 2: "Elementary Crystallography", Martin J. Buerger, John Wiley and Sons, New York, 1963. (out of print! But, you can find it in Library)
Reference 3: "The Basics of Crystallography and Diffraction", 2nd Edition, Christopher Hammond, Oxford Science Publications, New York 2001.
Reference 4: "Elements of X-ray Diffraction", 3nd Edition, B.D. Cullity, and S.R. Stock, Prentice Hall, NJ 2001.