Fejes, Zs., and L. Gerzson. “Development of Different Herbaceous Perennial Species on the Experimental Extensive Green Roof of Corvinus University Budapest”. International Journal of Horticultural Science 12, no. 1 (February 8, 2006): 85–89. Accessed November 29, 2021. https://ojs.lib.unideb.hu/IJHS/article/view/628.