Miller Indices are the convention used to label lattice planes. This mathematical description allows us to define accurately, planes within a crystal, and quantitatively analyse many problems in materials science.
 D. McKie and C. McKie, Crystalline Solids , Thomas Nelson and Sons, 1974.
A very comprehensive crystallography text.
 C. Hammond, The Basics of Crystallography and Diffraction , Oxford, 2001.
Chapter 5 covers lattice planes and directions. The rest of the book gives an introduction to crystallography and diffraction in general.
 B.D. Cullity, Elements of X-Ray Diffraction , Prentice Hall, 2003.
Covers X-Ray diffraction in detail. Chapter 2 covers the crystallography required for this.
 C. Kittel, Introduction to Solid State Physics, John Wiley and Sons, 2004.
Chapter 1 covers crystallography. The book then goes on to cover a wide range of more advanced solid state science.