O'Reilly is an electronic reference library by providing access to technical content from leading publishers, including books, videos, proven learning paths, case studies, interactive tutorials and audio books. The learning platform gives access to the latest titles from O'Reilly and from Pearson's collection of imprints which include: Addison-Wesley Professional, Adobe Press, Cisco Press, Macromedia Press, New Riders, Peachpit Press, Prentice Hall PTR, Sun Microsystems Press, Que, and Sams. Microsoft Press titles are also available in O'Reilly.

The goal of OAIster is to create a collection of previously difficult-to-access, academically-oriented digital resources that is easily searchable by anyone.

Open Syllabus is a non-profit research organization that collects and analyzes millions of syllabi to support novel teaching and learning applications. Open Syllabus helps instructors develop classes, libraries manage collections, and presses develop books. It supports students and lifelong learners in their exploration of topics and fields. It creates incentives for faculty to improve teaching materials and to use open licenses. It supports work on aligning higher education with job market needs and on making student mobility easier. It also challenges faculty and universities to work together to steward this important data resource. Open Syllabus currently has a corpus of nine million English-language syllabi from 140 countries. It uses machine learning and other techniques to extract citations, dates, fields, and other metadata from these documents. The resulting data is made freely available via the Syllabus Explorer and for academic research. The project was founded at The American Assembly, a public policy institute associated with Columbia University. It has been independent since 2019. All of the syllabi in the current collection are English language documents – including from universities where English is not the primary teaching language.

The OSF Preprints search combines records from various preprint repositories, including arXiv, bioRxiv, Cogprints, PeerJ, PsyArXiv, RePEc and SocArXiv.

Developed cooperatively with scholars and librarians worldwide, Oxford Bibliographies offers exclusive, authoritative research guides across a variety of subject areas. Combining the best features of an annotated bibliography and a high-level encyclopedia, this cutting-edge resource directs researchers to the best available scholarship across a wide variety of subjects.

Oxford Constitutions of the World (OCW) contains fully-translated English-language versions of all the world's constitutions (both national and sub-national), accompanied by individual jurisdictional commentaries, and supplementary materials, including foundation documents, historical versions of constitutions, and amendment Acts/Laws. The Max Planck Encyclopedia of Comparative Constitutional Law (MPECCOL) is a comprehensive online resource containing analytical comparative articles offering a global overview of constitutional law. Subscribers also benefit from access to the Oxford Law Citator, one of the most powerful tools available for legal research, enabling onward research and ease of access to key materials.

The Oxford English Dictionary is a guide to the meaning, history, and pronunciation of over half a million words and phrases, both present and past, from across the English-speaking world. It traces the usage of words through 3.5 million quotations from a wide range of international English language sources, from classic literature and specialist periodicals to film scripts, song lyrics and social media posts.

Oxford Handbooks Online is a collection of handbooks in 17 subject areas, bringing together the world's leading scholars to write review essays that evaluate the current thinking on a field or topic, and make an original argument about the future direction of the debate. For the first time, all Handbooks are available online as well is in print across the subject areas. Monthly updates introduce articles in advance of print publication and beyond the book, online-only content ensures the most current, authoritative coverage anywhere.

This historic journal index enables the simultaneous search in millions of citations for articles published in the arts, humanities and social sciences, across more than 300 years. It enables researchers quickly and comprehensively to identify articles relevant to their field of study and reduces what could take years of research to a matter of minutes. Journals indexed span 37 key subject areas and multiple languages.

Various dictionaries are available.

Preprint Citation Index is a multidisciplinary collection of preprints from a wide range of leading repositories, including arXiv, bioRxiv, chemRxiv, medRxiv, and Preprints.org. Currently, it provides more than 2 million articles ahead of the formal journal publication in the sciences, social sciences and arts & humanities. Papers from more than 20 repositories will be added in future. Within the Web of Science platform researchers can thus discover preprint records alongside peer-reviewed journal articles and other content sets. This simplifies the process of evaluating preprint quality and trustworthiness by connecting preprints to the versions of record or linking to other scholarly output from preprint authors and the citation network in Web of Science. Furthermore you can link directly to the preprint repositories to view each version of the preprint and download full texts.

The integration between ProQuest Dissertations & Theses Global with the Web of Science enables seamless discovery of early career, post-graduate research from all around the world, alongside records for journal articles, conference papers, book chapters, preprints, patents, and more. ProQuest Dissertations & Theses Citation Index makes more than 5.5 million multidisciplinary dissertations and theses searchable, from over 4,100 institutions and more than 60 countries, dating back to 1637. Researchers have simultaneous access to unpublished and published scholarship that helps them to discover emerging trends, identify new areas of research and find post-graduate programs engaged in cutting-edge research. For joint subscribers of the Web of Science and PQDT Global, direct full text linking from the Web of Science to the ProQuest platform is available, giving access to 3 million full-text works from thousands of universities. Additionally, cited reference indexing and linking helps to further connect dissertations and theses to related works and discover hard-to-find sources of research.

The PsycINFO databases cover the professional and academic literature in psychology and related disciplines including medicine, psychiatry, nursing, sociology, education, pharmacology, physiology, linguistics, and other areas. Coverage is worldwide, and includes references and abstracts to over 1300 journals and to dissertations in more than 30 languages, and to book chapters and books in the English language. Over 50,000 references are added annually. Popular literature is excluded.

"Psyndex - Literature & Audiovisual Media" contains records on psychology from researchers in Germany, Austria, and Switzerland. Compiled by the German Center for Documentation and Information in Psychology at the University of Trier (ZPID), this database covers German and English journal articles, books, chapters, reports, dissertations as well as audiovisual media. The database is bilingual: titles and descriptors are in German and English. German publications are abstracted in German; English publications in English. The database is indexed with the Thesaurus of Psychological Index Terms by permission of the American Psychological Association. A bilingual thesaurus is included with the database.

PubMed comprises over 29 million citations for biomedical literature from MEDLINE, life science journals, and online books. PubMed citations and abstracts include the fields of biomedicine and health, covering portions of the life sciences, behavioral sciences, chemical sciences, and bioengineering. PubMed also provides access to additional relevant web sites and links to the other NCBI molecular biology resources. PubMed is a free resource that is developed and maintained by the National Center for Biotechnology Information (NCBI), at the U.S. National Library of Medicine (NLM), located at the National Institutes of Health (NIH).

Designed for the digital world and an expanding universe of metadata users, "RDA: Resource Description and Access" is the new, unified cataloging standard. The online RDA Toolkit is the most effective way to interact with the new standard.

The SAO/NASA Astrophysics Data System (ADS) is a digital library portal for researchers in astronomy and physics, operated by the Smithsonian Astrophysical Observatory (SAO) under a NASA grant. The ADS maintains three bibliographic databases containing more than 13 million records covering publications in Astronomy and Astrophysics, Physics, and the arXiv e-prints. Abstracts and full-text of major astronomy and physics publications are indexed and searchable through the new ADS modern search form as well as a classic search form.

SciELO (Scientific Electronic Library Online) is a program of the Sao Paulo Research Foundation for the cooperative publishing of open access journals on the internet. Content includes regional journals from Latin American and the Caribbean as well as titles from Spain, Portugal and South Africa. The index covers approximately 650 titles (over 350 adding content to journals already covered in the Web of Science) and contains several million cited references.

ScienceOpen is a networking platform for scholars to enhance their research in the open, make an impact, and receive credit for it. The site provides advanced search and discovery functions, combined with post-publication peer review, recommendation, social sharing, and collection-building features. The Max Planck Society covers article-processing charges for ScienceOpen Research and ScienceOpen Poster centrally. Further details are available on the MPDL website.

Sciwheel is an advanced reference management system that provides assisting tools for discovery of research works, reading, annotation, as well as scientific and collaborative writing. It features a web-based application, a browser extension, citation tools for Microsoft Word and Google Docs, and a mobile application.