Hristovski, Slavčo, et al. “Belowground Phytomass and Production in the Beech Ecosystem Calamintho Grandiflorae-Fagetum in Mavrovo National Park. IV. Belowground Phytomass and Production of Herb Layer”. Macedonian Journal of Ecology and Environment, vol. 12, no. 1-2, Dec. 2009, pp. 3-8, http://mjee.org.mk/index.php/mjee/article/view/86.