Richard J. Butler (2012). "How do geological sampling biases affect studies of morphological evolution in deep time? A case study of the Pterosauria (Reptilia: Archosauria)". Evolution. 66 (1): 147-162. doi:10.1111/j.1558-5646.2011.01415.x. PMID22220871.
Richard J. Butler (2012). "How do geological sampling biases affect studies of morphological evolution in deep time? A case study of the Pterosauria (Reptilia: Archosauria)". Evolution. 66 (1): 147-162. doi:10.1111/j.1558-5646.2011.01415.x. PMID22220871.