Rothwell G. W.؛ Scheckler S. E.؛ Gillespie W. H. (1989). "Elkinsia gen. nov., a Late Devonian gymnosperm with cupulate ovules". Botanical Gazette. ج. 150 ع. 2: 170–189. DOI:10.1086/337763.
McLoughlin S.؛ Carpenter R.J.؛ Jordan G.J.؛ Hill R.S. (2008). "Seed ferns survived the end-Cretaceous mass extinction in Tasmania". American Journal of Botany. ج. 95 ع. 4: 465–471. DOI:10.3732/ajb.95.4.465. PMID:21632371.
McLoughlin S.؛ Carpenter R.J.؛ Jordan G.J.؛ Hill R.S. (2008). "Seed ferns survived the end-Cretaceous mass extinction in Tasmania". American Journal of Botany. ج. 95 ع. 4: 465–471. DOI:10.3732/ajb.95.4.465. PMID:21632371.