Lelesz, Judit Éva, and József Csajbók. “The Changes of the Purple coneflower’s (Echinacea Purpurea L.) Herb and Radix Drug Yield under Different Fertilization Conditions”. Acta Agraria Debreceniensis, no. 1, May 2019, pp. 79-83, https://doi.org/10.34101/actaagrar/1/2375.