A. Raichlen, David D. Gordon, Adam E. H. Harcourt-Smith, William D. Foster, Adam Randall Haas Jr, Wm. Proportional toe depths of human footprints. <p>p is preferred walk; f is fast walk; d is dry (6–8% water); w is wet (10–12% water).</p><p>Values are toe depths as a fraction of heel depth. P-values are for T-Tests comparing BKBH and extended (normal) datasets.</p> depths 2010-03-22
    https://plos.figshare.com/articles/dataset/_Proportional_toe_depths_of_human_footprints_/528114
10.1371/journal.pone.0009769.t001