Joly , K., R. R. Jandt, and D. R. Klein. “Decrease of Lichens in Arctic Ecosystems: The Role of Wildfire, Caribou, Reindeer, Competition and Climate in North-Western Alaska”. Polar Research, vol. 28, no. 3, Dec. 2009, pp. 433-42, doi:10.3402/polar.v28i3.6134.