Where to find free textbooks legally covers the general sources. This guide, which EdCitation publishes, goes one level down, to the free academic books online that belong to one field, from the medical library's book archive and a mathematical society's notes to the law casebooks and the classics.
Every source was read on its own pages on 23 September 2026, and each count is the one those pages gave that day; where a page is silent, this guide says so.
EdCitation sits at either end of that search. Before it, the Library is one catalogue of textbooks and scholarly books searched by discipline. After it, whichever site the book came from, Cite a source builds its reference free from the ISBN or the DOI.
Which free academic books exist for each discipline?
Fifteen sites hold free academic books for a named field; the twelve that carry most of them are in the table, the last column as the page states it or, where the page is silent, as the pages were read for this guide. The last row is EdCitation's own catalogue, which is not tied to one field.
| Discipline | Source | What it holds | Licence or terms | Account |
|---|---|---|---|---|
| Medicine, life sciences | NCBI Bookshelf | 9,000 titles | Per document | No |
| Mathematics, physics | AMS Open Math Notes | 260 notes and textbooks | Author's copyright | No |
| Computer science | Green Tea Press | 15 books by Allen B. Downey | Free licences, named per book | No |
| Law | CALI eLangdell | Casebooks, textbooks | Creative Commons | Name, email, law school to download |
| Law | H2O | Faculty-made casebooks | CC BY-NC-SA 3.0 | No; .edu or .gov email to author |
| Humanities, social sciences | OAPEN Library | 43,998 books, 7,465 chapters | Mostly CC BY-NC-ND or CC BY | No |
| Humanities, social sciences | Open Book Publishers | Monographs, textbooks | Free PDF and HTML | No |
| Humanities, social sciences | Project MUSE | Open access books | Set by each publisher | No |
| Humanities, social sciences | JSTOR | 16K+ open access titles | DRM-free | No |
| Business | OpenStax | 21 textbooks | Free online | No |
| Languages | COERLL | 16 languages | CC BY to CC BY-NC-ND | No |
| Classics | Perseus Digital Library | 2,412 works | CC ShareAlike 3.0 | No |
| Every discipline | EdCitation Library | Textbooks and scholarly books in one catalogue; with Max, read or borrow from more than 5 million books | Max plan, $24 a month | Yes |
Medicine and life sciences: what is on the NCBI Bookshelf?
The NCBI Bookshelf gives free access to the full text of books and documents in the biomedical and life sciences and health care, run by NCBI at the U.S. National Library of Medicine. Its overview, last updated in October 2023, counts 9,000 titles: textbooks, reference books, systematic reviews, clinical guidelines, technical reports and grey literature (National Center for Biotechnology Information, 2023).
Bookshelf is an archive, not a publisher: content comes from publishers and societies (45%), funders (45%) and conversion of authors' documents (10%), and is free to read from the day it is added, though "free access does not mean that there is no copyright protection" (National Center for Biotechnology Information, 2023). The copyright notice sends the reader to the licence line at the foot of each page, treats a document with no such line as public domain, and forbids systematic downloading (National Center for Biotechnology Information, 2016). The pages were read without a login.
StatPearls, as Bookshelf shows it
Bookshelf lists StatPearls as StatPearls [Internet], published by StatPearls Publishing in Treasure Island, Florida, dated "2026 Jan-", with a named editorial board and no article count. Its copyright line puts the whole book under CC BY-NC-ND 4.0, which permits distribution "provided that the article is not altered or used commercially" (StatPearls Publishing, 2026). Each article carries its own last-update date; cite that.
Mathematics and physics: where are the free books?
AMS Open Math Notes
The American Mathematical Society (n.d.-a) describes Open Math Notes as a repository of freely downloadable mathematical works; its search page showed 260 items on 23 September 2026. Three kinds sit together: drafts of course notes, textbooks and expositions, "subject to revision"; items from the Journal of Inquiry-Based Learning in Mathematics, a refereed journal; and refereed AMS publications, filtered by level and by 21 topics, mathematical physics among them.
The FAQ is candid: every set of notes is "reviewed and approved by AMS editors and the Open Math Notes Advisory Board", but the material "has not been copyedited or peer-reviewed" (American Mathematical Society, n.d.-b). Copyright stays with the author, and a Creative Commons licence applies only where the author has added one. No account is needed to download; an AMS login only to follow notes.
LibreTexts
Mathematics LibreTexts calls itself "a principal hub of the LibreTexts project", arranged as campus bookshelves, curated bookshelves and learning objects; its home page shows no count and no single licence, because the licence sits on each text (LibreTexts, n.d.-a).
Computer science: which publishers give their books away?
Green Tea Press
Green Tea Press is "free books by Allen B. Downey"; its home page lists 15 titles, among them Think Python, Think Java, Think Stats and Think Bayes, under "free licenses that allow you to copy and distribute the text" (Downey, n.d.-a). The licence is named book by book: the third edition of Think Python is CC BY-NC-SA 4.0, its HTML and PDF free, its print edition sold (Downey, n.d.-b). None needs an account.
MIT OpenCourseWare
MIT OpenCourseWare is "a free and open collection of material from thousands of MIT courses", over 2,500 of them, under CC BY-NC-SA 4.0, with no requirement to create an account (Massachusetts Institute of Technology, n.d.). Its books are lecture notes. OCW once kept an index of online textbooks; on 23 September 2026 that address redirected to an empty search, so this guide cannot say what it lists now.
Law: where are the free casebooks?
CALI eLangdell Press
The eLangdell bookstore, run by CALI, the Center for Computer-Assisted Legal Instruction, describes its casebooks and textbooks in three phrases: "100% Free. Creative Commons licensed. Peer-reviewed." (Center for Computer-Assisted Legal Instruction, n.d.). Contracts, torts, criminal procedure, constitutional law, tax and copyright are among the subjects. The page names no Creative Commons variant; its download form asks for a name, email address, law school and agreement to its terms.
H2O Open Casebooks
H2O is "offered by the Harvard Law School Library, through its Library Innovation Lab": faculty authors build casebooks from U.S. court decisions supplied through CourtListener and the Caselaw Access Project, free to read and adaptable under CC BY-NC-SA 3.0 (Harvard Law School Library, n.d.). "Anybody with an internet connection can read an H2O casebook"; an account with a .edu or .gov address is needed only to author, remix or annotate one.
Humanities and social sciences: which open access book libraries are free?
Four, and they overlap.
OAPEN Library
The OAPEN Foundation calls OAPEN an infrastructure for "peer-reviewed open access books"; its home page counts 40,000+ books from 450+ publishers in 80+ languages (OAPEN Foundation, n.d.-a). The library counted higher on the same day, 43,998 books and 7,465 chapters, and its filters give the licences: 22,016 items CC BY-NC-ND, 15,281 CC BY, 3,884 CC BY-NC, 2,698 CC BY-SA and 1,747 all rights reserved (OAPEN Foundation, n.d.-b). No login is needed to read; an account only raises the export limit.
Open Book Publishers
Open Book Publishers (n.d.) is a scholar-led, non-profit open access press in the UK, founded in 2008, that charges authors nothing and publishes "rigorously peer-reviewed" monographs, textbooks and translations, free in PDF and HTML, with paperbacks, hardbacks and EPUBs sold. Its about page gives no title count.
Project MUSE and JSTOR
Project MUSE (n.d.), run by Johns Hopkins University Press with the Milton S. Eisenhower Library, hosts open access books from university presses, scholarly societies and not-for-profit publishers; they are DRM-free, access "requires no login or registration", the publishers set the licence, and no count is given.
JSTOR, part of the non-profit ITHAKA, offers "thousands of DRM-free open access ebooks" free without an account (JSTOR, n.d.-a); its librarians' page says 16K+ titles from 165+ publishers, for "unlimited, DRM-free, and perpetual use" (JSTOR, n.d.-b). Neither page names a licence or says peer reviewed.
Engineering, business and languages: what is free?
OpenStax's business page listed 21 textbooks under seven headings on 23 September 2026, from Principles of Accounting to Business Law I Essentials, Principles of Economics and Principles of Marketing, all "100% free online" (OpenStax, n.d.); the licence is in the leader guide. Engineering LibreTexts is another hub of the same project as the mathematics library, its licence shown on each text (LibreTexts, n.d.-b).
COERLL, the Center for Open Educational Resources and Language Learning at the University of Texas at Austin, lists courses, textbooks, grammars and corpora in 16 languages: Arabic, Mandarin, Croatian, Czech, French, German, Hindi, Italian, K'iche', Nahuatl, Portuguese, Quechua, Russian, Spanish, Turkish and Yoruba, including Français interactif, a first-year French course with over 320 videos (COERLL, n.d.). The licences run from CC BY to CC BY-NC-ND and differ by item.
History and classics: Perseus and Project Gutenberg
The Perseus Digital Library is "a non-profit enterprise, located in the Department of Classical Studies, Tufts University"; its home page counts 2,412 works, 1,639 in Greek and 636 in Latin, and 69.7 million words, as of 22 November 2022 (Perseus Digital Library, n.d.-a). The texts are under a Creative Commons ShareAlike 3.0 licence, linked as CC BY-SA 3.0 (Perseus Digital Library, n.d.-b). Perseus 4.0 is no longer under active development while Perseus 6 is built, so cite the edition you read and its URL. For older editions in history and literature, Project Gutenberg holds more than 75,000 free ebooks (Project Gutenberg, n.d.); how to cite one is in the leader guide.
How do I judge a free book before citing it in a paper?
Peer review or editorial control, as the source states it
Bookshelf admits a title only if it has "a clearly stated peer-review process" (National Center for Biotechnology Information, 2021), but once a title is in, NLM "does not review, evaluate, or judge the quality of individual articles" (National Center for Biotechnology Information, 2016). Open Book Publishers, OAPEN and eLangdell say peer-reviewed. Open Math Notes says the opposite in plain words: approved by editors, not peer-reviewed. H2O and JSTOR say nothing.
Edition and date
A free book moves more than a paid one. StatPearls updates article by article; Open Math Notes are "subject to revision", with earlier versions kept in each note's archive; an H2O casebook can be cloned and changed; a LibreTexts page has no edition. Record the edition, the copyright-page or last-update date, and the date you read it.
Cite it by ISBN or DOI
APA 7 uses one format for print and ebooks: the platform is never named, the year is the copyright page's, the edition goes in parentheses after the title, a DOI follows the publisher, and an ebook without a DOI takes its stable URL, never the database's name (American Psychological Association, 2020). In practice, for a book from any of the sites above:
- Find the identifier on the book's own copyright page or landing page: a DOI if it has one, otherwise the ISBN of the edition you read.
- Paste it into EdCitation's Cite a source and choose the style your course uses; it offers six, APA 7 and MLA 9 among them. A DOI draws the reference from the publisher's record. An ISBN sends it to Open Library, where the author names are read from the record of that particular edition, which is why the edition matters in step 1.
- Read the title against the book. Cite a source sets the title in sentence case, as APA 7 asks, and keeps names and initialisms; glance at any name made of ordinary words.
- Add what only you know: for an ebook with no DOI, the stable URL of the page you read it on; for StatPearls or another book updated in parts, the date of the part you used.
When the list is done, Verify references checks it, free; what a DOI is explains the identifier.
Is there one place to search books of every discipline and cite them?
Yes: EdCitation's Library. For a student who wants the books of every discipline and the citation together, it is the best tool, and the reason is in the fifteen sites above: fifteen search boxes, fifteen kinds of record, and licences that change from site to site and often from book to book, against one catalogue of textbooks and scholarly books searched by discipline, kind, language and year. The catalogue lets you buy a paid title, locate a copy in a library near you and keep every book you want in My Books, in one place, and the Max plan adds reading or borrowing from more than 5 million books.
Why the reference should come from the record
A chatbot asked for a book reference writes one, and no chatbot can look the edition up the way Cite a source does, by its ISBN or DOI, before a word of the entry is set. EdCitation never writes a reference. That matters more for free books than for most: as the section on edition and date showed, StatPearls changes article by article and an H2O casebook can be cloned and altered, so the entry has to describe the version you actually read, and the ISBN or DOI of that version is what ties it there.
What it costs
Max, the plan that carries the Library, is $24 a month or $216 a year and brings Theoretics QA as well. Nothing on the citing side costs anything: Cite a source, Find sources and Verify references work on the site without an account. Pro, at $8 a month, adds References from a file, Mechanics QA, Check plagiarism and Check AI; every plan is on Pricing.
Quick questions
Is the NCBI Bookshelf free to use?
Yes. Every book and document is free to read without a login, but each keeps its own copyright terms, shown at the foot of its pages.
Is StatPearls peer reviewed?
Bookshelf admits a title only with a clearly stated peer-review process and lists StatPearls with a named editorial board, but NLM does not itself review individual articles, so check any figure against the source the article cites.
Are open access books peer reviewed?
Only when the site says so: OAPEN and Open Book Publishers describe their books as peer-reviewed; JSTOR's open access pages say nothing. Check the book's front matter.
Can I cite a free ebook the same way as a print book?
Yes. APA 7 uses one format for both and never names the platform. Give author, year, title, edition and publisher, then the DOI or, failing that, the stable URL. EdCitation's free Cite a source builds the entry from the book's DOI or ISBN and sets the title in sentence case, as APA 7 asks.
References
- American Mathematical Society. (n.d.-a). Open Math Notes [Home page]. Retrieved 23 September 2026, from https://www.ams.org/open-math-notes
- American Mathematical Society. (n.d.-b). Open Math Notes: FAQ. Retrieved 23 September 2026, from https://www.ams.org/open-math-notes/omn-faq
- American Psychological Association. (2020). Book/ebook references. APA Style. https://apastyle.apa.org/style-grammar-guidelines/references/examples/book-references
- Center for Computer-Assisted Legal Instruction. (n.d.). The eLangdell bookstore. CALI. Retrieved 23 September 2026, from https://www.cali.org/the-elangdell-bookstore
- COERLL. (n.d.). Materials. University of Texas at Austin. Retrieved 23 September 2026, from https://www.coerll.utexas.edu/coerll/materials
- Downey, A. B. (n.d.-a). Green Tea Press: Free books by Allen B. Downey [Home page]. Retrieved 23 September 2026, from https://greenteapress.com/wp/
- Downey, A. B. (n.d.-b). Think Python, 3rd edition. Green Tea Press. Retrieved 23 September 2026, from https://greenteapress.com/wp/think-python-3rd-edition/
- Harvard Law School Library. (n.d.). About H2O. H2O Open Casebooks. https://about.opencasebook.org/
- JSTOR. (n.d.-a). Open access and free content on JSTOR. ITHAKA. Retrieved 23 September 2026, from https://about.jstor.org/products/jstor-platform/whats-on-jstor/open-and-free/
- JSTOR. (n.d.-b). Open access books on JSTOR. ITHAKA. Retrieved 23 September 2026, from https://about.jstor.org/products/books/open-access/
- LibreTexts. (n.d.-a). Mathematics LibreTexts [Home page]. Retrieved 23 September 2026, from https://math.libretexts.org/
- LibreTexts. (n.d.-b). Engineering LibreTexts [Home page]. Retrieved 23 September 2026, from https://eng.libretexts.org/
- Massachusetts Institute of Technology. (n.d.). About OCW. MIT OpenCourseWare. https://ocw.mit.edu/about/
- National Center for Biotechnology Information. (2016). Bookshelf copyright notice. In About Bookshelf. National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/n/about/copyright/
- National Center for Biotechnology Information. (2021). Content selection for Bookshelf. In About Bookshelf. National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/n/about/scientificeval/
- National Center for Biotechnology Information. (2023). Bookshelf overview. In About Bookshelf. National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/n/about/overview/
- OAPEN Foundation. (n.d.-a). OAPEN [Home page]. Retrieved 23 September 2026, from https://www.oapen.org/
- OAPEN Foundation. (n.d.-b). OAPEN Library [Home page]. Retrieved 23 September 2026, from https://library.oapen.org/
- Open Book Publishers. (n.d.). About us. https://www.openbookpublishers.com/about
- OpenStax. (n.d.). Browse free business textbooks. Rice University. Retrieved 23 September 2026, from https://openstax.org/subjects/business
- Perseus Digital Library. (n.d.-a). Perseus Digital Library [Home page]. Tufts University. Retrieved 23 September 2026, from https://www.perseus.tufts.edu/hopper/
- Perseus Digital Library. (n.d.-b). Perseus downloads. Tufts University. Retrieved 23 September 2026, from https://www.perseus.tufts.edu/hopper/opensource/download
- Project Gutenberg. (n.d.). About Project Gutenberg. Retrieved 23 September 2026, from https://www.gutenberg.org/about/
- Project MUSE. (n.d.). Open access overview. Johns Hopkins University Press. https://about.muse.jhu.edu/muse/open-access-overview/
- StatPearls Publishing. (2026). StatPearls. National Center for Biotechnology Information, Bookshelf. Retrieved 23 September 2026, from https://www.ncbi.nlm.nih.gov/books/NBK430685/