Head Rubbing and Licking Reinforce Social Bonds in a Group of Captive African Lions, Panthera leo Matoba, Tomoyuki ; Kutsukake, Nobuyuki ; Hasegawa, Toshikazu Abstract Publication: PLoS ONE Pub Date: September 2013 DOI: 10.1371/journal.pone.0073044 Bibcode: 2013PLoSO...873044M