Taxon - Links and literature
Novikoff A., Barabasz-Krasny B. (2015): System of Embryophytes [https://phytomorphology.org/personal-inf...], Plant Systematics: 23-63. Liga-Pres [as Progymnospermopsida Beck]Data retrieved on: 4 January 2020
The Interim Register of Marine and Nonmarine Genera [1442]
Rees, T. (compiler): The Interim Register of Marine and Nonmarine Genera [https://www.irmng.org] [as Progymnospermopsida]
Data retrieved on: 4 January 2020
Wikipedia Articles [Progymnosperm]
Wikipedia Articles [https://en.wikipedia.org] [as Progymnospermopsida]