Australian National Herbarium Fern Pages: Comprehensive information about the taxonomy and distribution of Australian and Papuasian ferns and allies, as well as general information about pteridophytes.
British Pteridological Society: Images and information about ferns and other pteridophytes; activities of the society including publication of the Fern Gazette, Pteridologist, and Bulletin.
Checklist of World Ferns: A compiled list of the ferns and fern allies of the world, with full botanical names, information about where they are found, and their classification.
Field Systematic Botany - Pteridophytes: an Overview: A detailed introduction to the ferns and fern allies.
Images of Pteridophyta: Part of the W3Tropicos database at the Missouri Botanical Garden.
Introduction to the Pteridophytes: An illustrated introduction to the ferns and fern allies for undergraduate students.
Natural Perspective - Ferns and Allies (Filicinophyta): Brief introduction.
Pteridophytes: Ferns and Fern Allies: Personal site with a classification scheme, bibliography, some local checklists (Ohio and Kentucky), and an article on ferns and soil conservation.
Pteridophytes: The Ferns and their Allies: A classification of the ferns and their allies - a work in progress at the Australian National Herbarium.