—— Lichens of N. W. Minnesota. Tom. cit. pp. 657-709³.
—— Lichens of the Northern Boundary. Op. cit. III. pp. 167-236, 1903.
—— Composition of a Desert Lichen Flora. Mycologia, I. pp. 87-109, 1909.
—— Some Common Types of Lichen Formations. Torrey Bot. Club, XXX. pp. 412-418, 1903.
—— A Lichen Society of a Sandstone Rip-rap. Bot. Gaz. XXXVI. pp. 265-284 (5 figs.), 1904.
—— The Nature and Classification of Lichens. I. Mycologia, III. pp. 231-269, 1911; II. Op. cit. V. pp. 97-116, 1913.
—— The rate of Growth and Ecesis in Lichens. Mycologia, IX. pp. 138-158, 1917.
—— A new genus and species of the Collemaceae. Mycologia, X. pp. 235-238 (1 pl.), 1918.
Fischer, Ed. Beiträge zur Kenntniss exotischen Pilze. Hedwigia, XXIX. pp. 161-171 (1 pl.), 1890.
Fitting, N. Ueber die Beziehungen zwischen den epiphyllen Flechten und den von ihnen bewohnten Blättern. Ann. Jard. Bot. Buitenzorg, Suppl. 3, pp. 505-519, 1910.