J. H. D.  Wolf, ?Diversity Patterns and Biomass of Epiphytic Bryophytes and Lichens Along an Altitudinal Gradient in the Northern Andes?, Annals of the Missouri Botanical GardenAnnals of the Missouri Botanical Garden, vol. 80, pp. 928-960, 1993.

J. H. D.  Wolf, ?Diversity Patterns and Biomass of Epiphytic Bryophytes and Lichens Along an Altitudinal Gradient in the Northern Andes?, Annals of the Missouri Botanical GardenAnnals of the Missouri Botanical Garden, vol. 80, pp. 928-960, 1993.