Partner Choice in Raven (Corvus corax) Cooperation Asakawa-Haas, Kenji ; Schiestl, Martina ; Bugnyar, Thomas ; Massen, Jorg J. M. Abstract Publication: PLoS ONE Pub Date: June 2016 DOI: 10.1371/journal.pone.0156962 Bibcode: 2016PLoSO..1156962A