Daniel E. Lieberman, Madhusudhan Venkadesan, William A. Werbel, Adam I. Daoud, Susan D'Andrea, Irene S. Davis, Robert Ojiambo Mang'eni, and Yannis Pitsiladis. 1/28/2010. “Foot strike patterns and collision forces in habitually barefoot versus shod runners.” Nature, 463, Pp. 531-536.