Randlane, T., I. Jüriado, A. Suija, P. Lõhmus, and E. Leppik. “Lichens in the New Red List of Estonia”. Folia Cryptogamica Estonica, Vol. 44, 1, pp. 113-20, https://ojs.utlib.ee/index.php/FCE/article/view/13713.