This book offers a comprehensive exposition of modern analysis of causation. It shows how causality has grown into a mathematical theory with significant applications in the fields of statistics, artificial intelligence, economics, philosophy, cognitive science, and the health and social sciences. Propensity Scores are discussed in detail from Page 348 in the unit titled Understanding Propensity Scores.
Pearl J (2009) “Understanding propensity scores”. In Causality: Models, Reasoning, and Inference. (Cambridge: Cambridge University Press). Retrieved from http://www.cambridge.org/aus/catalogue/catalogue.asp?isbn=9780521895606