Purnomo, Eko, et al. “Analyzing Causes of the Death of Ferns (Pteridophyta) in the Padang Savana, Taman Nasional Bromo Tengger Semeru (TN-BTS)”. Journal of Natural Sciences and Mathematics Research, vol. 7, no. 2, Dec. 2021, pp. 73-78, https://journal.walisongo.ac.id/index.php/JNSMR/article/view/11074.