Katz, Emma J, and Carla J Essenberg. “The Effect of the Dispersion of Rewarding and Rewardless Flowers on Visitation and Constancy by Bumblebees (Bombus Impatiens)”. Journal of Pollination Ecology, vol. 23, Aug. 2018, pp. 119-26, doi:10.26786/1920-7603(2018)14.