Pollination Services Provided by Bees in Pumpkin Fields Supplemented with Either Apis mellifera or Bombus impatiens or Not Supplemented Petersen, Jessica D. ; Reiners, Stephen ; Nault, Brian A. Abstract Publication: PLoS ONE Pub Date: July 2013 DOI: 10.1371/journal.pone.0069819 Bibcode: 2013PLoSO...869819P