Violina R. Angelova and  Mariana N. Perifanova-Nemska and  Galina P. Uzunova and  Krasimir I. Ivanov and  Huu Q. Lee,  Potential of Sunflower (Helianthus annuus L.) for Phytoremediation of Soils Contaminated with Heavy Metals.   journal   = {International Journal of Environmental and Ecological Engineering}, [online]. World Academy of Science, Engineering and Technology.
    July 2016, vol. 117(9). 576 - 583
    [viewed 11 April 2021]. Available from: https://publications.waset.org/pdf/10005333.