"The Inefficient Stock Market - What Pays Off And Why". Book by Robert Haugen, ch. 3, Estimating Portfolio Risk and Expected Return with Ad Hoc Factor Models, p. 29, 1999.
"Leslie Mann and Paul Rudd Talk THIS IS 40, Turning 40 Themselves, and Preparing for Awkward Scenes". Interview with Christina Radish, collider.com. December 16, 2012.