Conkright, Margarita E.; Sackett, W. M. (1992): Stable carbon isotope changes during the maturation of organic matter. Columbia University Press, New York, NY, United States, In: Whelan, Jean K. (editor), Farrington, John W. (editor), Organic matter; productivity, accumulation, and preservation in Recent and ancient sediments, 403-414, georefid:1994-032724