Avalon Project - “digital documents relevant to the fields of Law, History, Economics, Politics, Diplomacy and Government.”
BioMed Central Almost 300 peer-reviewed journals in all aspects of biology and medicine.
Calisphere Over 750,000 images, texts, and recordings from California’s libraries, museums and archives.
Churchill Archive “...source material for British and world history in the late nineteenth and early twentieth centuries.”
CIA World Factbook THE source for current statistics and information about the nations of the world.
Database of Open Access Journals Just what it says, “ca. 9000 open access journals covering all areas of science, technology, medicine, social science and humanities.”
Digital Public Library of America “... a collection of millions of cultural heritage objects from libraries, archives, and museums across the country.”
Google Scholar “From one place, you can search across many disciplines and sources: articles, theses, books, abstracts and court opinions, from academic publishers, professional societies, online repositories, universities and other web sites.” Use this with Unpaywall, described below.
Internet History Sourcebooks Project “is a collection of public domain and copy-permitted historical texts presented cleanly (without advertising or excessive layout) for educational use.”
LearnTechLib Over 100,000 articles and abstracts focusing on learning and technology.
Infotopia “...an academic search engine accessing only trusted websites previously selected by librarians, teachers, and library and educational consortia.”
Library of Congress American Memory Project “...provides free and open access through the Internet to written and spoken words, sound recordings, still and moving images, prints, maps, and sheet music that document the American experience. It is a digital record of American history and creativity.”
OAPEN “...freely accessible academic books, mainly in the area of humanities and social sciences.”
PBS LearningMedia “...provides PreK-12 educators with access to free digital content…”
ProCon.org “...provides professionally-researched pro, con, and related information on more than 50 controversial issues…”
Project Gutenberg The oldest digital library, PG was founded in 1971 as a project to digitize books in the public domain. It currently contains more than 53,000 free ebooks.
Public Domain Review A project of the Open Knowledge Foundation, the PDR is an online journal and project that includes curated collections of images, books, audio and film, as well as in-depth essays from experts, mainly in the areas of the arts and literature.
Public Library of Science (PLOS) “...a nonprofit Open Access publisher, innovator and advocacy organization....”
Sci-Hub A controversial website that hosts millions of articles obtained by bypassing publisher paywalls.
Wilson Center - International History Declassified - “contains once-secret documents from governments all across the globe, uncovering new sources and providing fresh insights into the history of international relations and diplomacy. “