Wonderful Life: The Burgess Shale and the Nature of History Stephen Jay Gould. 1989. Wonderful Life: The Burgess Shale and the Nature of History. :347.
Toward a Historical Sociology of Social Situations David Diehl, Daniel McFarland. 2010. Toward a Historical Sociology of Social Situations. American Journal of Sociology. 115(6):1713-1752.