HOLONEC, L., F. RANGA, D. CRAINIC, A. TRUTA, and C. SOCACIU. “Evaluation of Betulin and Betulinic Acid Content in Birch Bark from Different Forestry Areas of Western Carpathians”. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, Vol. 40, no. 2, Nov. 2012, pp. 99-105, doi:10.15835/nbha4027967.