BioStor
 | A list of the ferns and fern allies of North America north of Mexico, with principal synonyms and distribution William R Maxon (1901) Proceedings of The United States National Museum 23: 619-651 |
 | ∑Miocene fossil woods from the Columbia basalts of Central Washington. J. Arnold Arb. 42: 165--203. U & E S Barghoorn Prakash (1961) Journal of the Arnold Arboretum 42: 165-203 |
 | Augustus Fendler's Venezuelan Collections of Ferns and Fern Allies Alan R Smith and Carol A Todzia (1989) Annals of the Missouri Botanical Garden 76: 330-349 |
 | Leon Croizat's Plant Collections from the Franco-Venezuelan Expedition to the Headwaters of the Rio Orinoco Bruce K Holst and Carol A Todzia (1990) Annals of the Missouri Botanical Garden 77: 485-516 |