Bibliografy fan de Fryske taal- en literatuerwittenskip (Bibliography of Frisian Language and Literature, BFTL) contains titles of books, articles, book chapters and reviews from 1940 to date (no full text).
Digital Library for Frisian Literature (Digitale Bibliotheek voor de Nederlandse Letteren/Friese Literatuur) contains literary texts from 17th Century to date.
The series Altfriesische Rechtsquellen (a critical text edition of the main Old Frisian manuscripts) is available in full text from Deutsches Rechtswörterbuch (DRW) (search by title in 'Digitalisate')
Tresoar comprises the Frisian Library, Archives and Literary Museum. It holds Frisian books, manuscripts, maps, images and archival material.
Sirkwy Frisian literay website contains modern literary works in full text as well as news on recent publications.
Ensafh Frysk Literêr Tydskrift Digital Literary journal
Handbook of Frisian Studies, ed. by H.H.Munske and N.Arhammer (2001), available in the Taylor Institution Library
Tresoar (in the Netherlands) offers further reference material, including biographies and bibliographies of authors, films, plays, and resources in full text. West-Frisian, East-Frisian and North Frisian are covered. The Digital Collection contains a large number of digitised manuscripts, archival materials and old printings.
The Nordfriisk Instituut offters more detailed information on the North-Frisian language.