J. E.  Richardson, Chatrou, L. W., Mols, J. B., Erkens, R. H. J., and Pirie, M. D., ?Historical biogeography of two cosmopolitan families of flowering plants: Annonaceae and Rhamnaceae.?, Philosophical Transactions of the Royal Society of London B series, vol. 359, pp. 1495-1508, 2004.