Hernandez, X. E., Orden, A. A., Giordano, O. S., & Kurina, M. (2005). Effects of elicitor and copper sulfate on grindelic acid production in submerged cultures of Grindelia pulchella. Electronic Journal of Biotechnology, 8(3), 0–0. Retrieved from https://www.ejbiotechnology.info/index.php/ejbiotechnology/article/view/v8n3-6