Marmor, L., T. Tõrra, E. Leppik, L. Saag, and T. Randlane. “Epiphytic Lichen Diversity in Estonian and Fennoscandian Old Coniferous Forests”. Folia Cryptogamica Estonica, vol. 48, Oct. 2011, pp. 31-43, https://ojs.utlib.ee/index.php/FCE/article/view/13631.