Morgan, Michael J. Visual Perception, Max Planck Fellow, Max Planck Institute for Metabolism Research, Managing Director: Jens Brüning, Max Planck Society;
Dakin, S. C., Tibber, M. S., Greenwood, J. A., Kingdom, F. A. A., & Morgan, M. J. (2011). A common visual metric for approximate number and density. Proceedings of the National Academy of Sciences of the United States of America, 108(49), 19552-19557. doi:10.1073/pnas.1113195108.