BioStor
 | The families of cycads and the Zamiaceae of Australia L A S Johnson (1959) Proceedings of The Linnean Society of New South Wales 84: 64-117 |
 | The Metasequoia flora and its phytogeographic significance S Y Hu (1980) Journal of the Arnold Arboretum 61: 41-94 |
 | Phylogenetic Analysis of Seed Plants and the Origin of Angiosperms Peter R Crane (1985) Annals of the Missouri Botanical Garden 72: 716-793 |