Y.  Si, Skidmore, A. K., Wang, T., de Boer, W. F., Toxopeus, A. G., Schlerf, M., Oudshoorn, M., Zwerver, S., Van Der Jeugd, H., Exo, K. - M., and Prins, H. H. T., ?Distribution of Barnacle Geese Branta leucopsis in Relation to Food Resources, Distance to Roosts, and the Location of Refuges?, Ardea, vol. 99, pp. 217?226, 2011.