Dibble, A.C., Miller, N.G., Hinds, J.W., Fryday, A.M., 2009. Lichens and Bryophytes of the Alpine and Subalpine Zones of  Katahdin, Maine, I: Overview, Ecology, Climate and Conservation Aspects. Bryologist 112, 651-672. doi:10.1639/0007-2745-112.4.651