K. Friston, J. Ashburner, S. Kiebel, T. Nichols, and W. Penny Statistical Parametric Mapping: The analysis of functional brain images. Elsevier, London, 2006.
R.S.J. Frackowiak, K.J. Friston, C. Frith, R. Dolan, C.J. Price, S. Zeki, J. Ashburner, and W.D. Penny. Human Brain Function. Academic Press, 2nd edition, 2003.
All chapters from this book are available from the SPM Website