Denisow, Bozena, et al. “Nectar and Pollen Production of Helianthus Tuberosus L. – an Exotic Plant With Invasiveness Potential”. Acta Botanica Croatica, vol. 78, no. 2, Oct. 2019, https://ojs3.abc.botanic.hr/index.php/abc/article/view/2510.