Legg David A, Ma Xiaoya, Wolfe Joanna M, Ortega-Hernández Javier, Edgecombe Gregory D, Sutton Mark D
Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ UK.
Nature. 2011 Aug 10;476(7359):E2-3; discussion E3-4. doi: 10.1038/nature10267.