Bornet, (E.), “Recherches sur les Gonidies des Lichens,” in “Ann. des Sci. Nat.” 1873, 5 sér. vol. xvii.
Nylander, “On the Algo-Lichen Hypothesis,” &c., in “Grevillea,” vol. ii. (1874), No. 22, p. 146.
In Regensburg “Flora,” 1870, p. 92.
Rev. J. M. Crombie, in “Popular Science Review,” July, 1874.
Berkeley’s “Introduction to Cryptogamic Botany,” p. 373, fig. 78a.