Simpson, G (1949). "Tempo and Mode in Evolution". Transactions of the New York Academy of Sciences. 8. New York: Columbia University Press: 45–60. doi:10.1111/j.2164-0947.1945.tb00215.x. PMID21012247.
Simpson, G (1949). "Tempo and Mode in Evolution". Transactions of the New York Academy of Sciences. 8. New York: Columbia University Press: 45–60. doi:10.1111/j.2164-0947.1945.tb00215.x. PMID21012247.