Ko Wang & Marvin L. Wolverton 
Real Estate Valuation Theory [PDF ebook] 

Real Estate Valuation Theory is organized around five categories of intellectual contribution to the whole-appraiser decision making and valuation accuracy, application of nontraditional appraisal techniques such as regression and the minimum-variance grid method, appraising contaminated property, ad valorem tax assessment, and new perspectives on traditional appraisal methods. One common thread is that all of the papers are exceptionally well written and thought provoking.