Bell, N. E.; Hyvonen, J. (2010). "A phylogenetic circumscription of Polytrichastrum (Polytrichaceae): Reassessment of sporophyte morphology supports molecular phylogeny". American Journal of Botany. 97 (4): 566–78. doi:10.3732/ajb.0900161. PMID21622419.
Bell, N. E.; Hyvonen, J. (2010). "A phylogenetic circumscription of Polytrichastrum (Polytrichaceae): Reassessment of sporophyte morphology supports molecular phylogeny". American Journal of Botany. 97 (4): 566–78. doi:10.3732/ajb.0900161. PMID21622419.