Varenflora
- Ferns from Florida, New Jersey, New York, and New England / Mike Rosenthal [us]
- Common Ferns and Fern-Ally species / Northwestern Ontario Forest [ca]
- Ferns of the Canberra Region [au]
- Wikipedia, The Free Encyclopedia Varens, Nederlands [us]
- Wikipedia, The Free Encyclopedia Ferns, Engels [us]
- Ferns in Britain and Ireland / Roger Golding [uk]
- Fougères du Vercors [fr]
- Te Ara / The Encyclopedia of New Zealand [nz]
- The fern genus Polystichum Koos Roux [za]