Caplin, Andrew; Schotter, Andrew (编). The Foundations of Positive and NormativeEconomics: A Handbook. Oxford University Press. 2008. ISBN 978-0-19-532831-8
乎是與非,而非應該與否。與實證陳述相對的是包含價值判斷的規範陳述(英语:Normative statement)。 Lipsey, Richard G. An introduction to positive economics fourth. Weidenfeld & Nicolson. 1975:
Encyclopedia on Law & Economics. Georgakopoulos, Nicholas L. (2005). Principles and Methods of Law and Economics: Basic Tools for Normative Reasoning (Cambridge