Dating rock surfaces by lichen growth and its application to glaciology and physiography (lichenometry), Raasch, G.O., ed., Geology of the Arctic
Beschel, R.E., 1961, Dating rock surfaces by lichen growth and its application to glaciology and physiography (lichenometry), Raasch, G.O., ed., Geology of the Arctic: University of Toronto Press, v. 2, p. 1044-1062.