The Stormont Administration ran Northern Ireland as a province of the UK from 1921-72. This digital resource offers fulltext searching of facsimile images of the complete record of Stormont from the Public Record Office of Northern Ireland, along with new interpretative essays and resources. "CAB 4" represents a unique record of "how government actually works" through turbulent and often violent times.

Novoe russko slovo (The New Russian Word), published in New York since 1910, was a daily Russian newspaper until 2009, when it went weekly. In the 1920s, it shed its pro-Communist sympathies establishing itself as the premier newspaper of the Russian émigré community in New York and beyond. Due to financial difficulties and other less direct factors, the oldest Russian language periodical in North America ceased publication in 2010. Its full text archive is available for digital access via the East View platform.

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.

The OAPEN Library contains freely accessible academic books, mainly in the area of Humanities and Social Sciences. OAPEN works with publishers to build a quality controlled collection of Open Access books, and provides services for publishers, libraries and research funders in the areas of dissemination, quality assurance and digital preservation. OAPEN serves as delivery platform for various open access initiatives, including Knowledge Unlatched.

OECD iLibrary is the online library of the Organisation for Economic Cooperation and Development (OECD) featuring its books, papers and statistics and is the gateway to OECD’s analysis and data. It also contains content published by the International Energy Agency (IEA), the Nuclear Energy Agency (NEA), the OECD Development Centre, PISA (Programme for International Student Assessment), and the International Transport Forum (ITF).

"Ogonek" is one of the oldest weekly magazines in Russia and has been published continuously since 1923. It contains illustrated articles on politics, culture and economy, interviews and photo reports.

Olms Online is an e-book portal providing access to following collections: * Reprints: About 400 volumes with a focus on German language and literature and on philosophy. Olms Online presents titles with additional information. These are reprints with new introductions, afterwords, notes or indexes added by the editors. * Frankfurt and Leipzig Book Fair Catalogues: Book-trade catalogues, generally referred to as book fair catalogues, offer a unique overview of German and European book production over a period of nearly 300 years (1594-1860).

The Open Library of Humanities is an open access publishing platform, launched as an international network of scholars, librarians, programmers and publishers in January 2013. The OLH platform supports academic journals from across the humanities disciplines, as well as hosting its own multidisciplinary journal. Unlike many open-access publishers, the Open Library of Humanities does not charge individual author fees, but covers all costs by cooperating with an international library consortium.

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.

Founded in 1916, Optica (formerly the Optical Society of America, OSA) was organized to increase and diffuse the knowledge of optics, pure and applied. One of the Society's major activities is the publication of peer-reviewed journals and books. Though access to current Optica Publishing Group content is no longer licensed, access to the 2007 - 2011 volumes of the journals and proceedings is still available.

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 platform serves as interface to over 300 journals published by the Oxford University Press (OUP) in the humanities, social sciences, law, science, and medicine. Two-thirds of this journals are published in partnership with learned and professional societies around the world. The MPG subscription enables full text access to OUP's full journal collection. It also covers article-processing charges for Max Planck authors in hybrid and selected fully open access journals offering CC-BY licenses. Further details are available on the MPDL website.

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.

Including Oxford Scholarship Online (OSO), the University Press Scholarship Online (UPSO) publishes new books every month from an ever-growing roster of contributing presses, each adding to the variety of subjects covered on the platform. The MPG purchased the volumes 2003-2013/2014 of 16 OSO subject collections. This selection is continuously extended by single e-book acquisitions by MPG libraries.

Facsimile edition of the "Patrologia Graeca", edited by Jacques-Paul Migne from 1857 to 1866 in more than 160 volumes. The database comprises works of the Greek church literature beginning with Pseudo-Clemens (100 AD) up to Kallistos (1478) and thus makes available the important Greek Christian authors and the most influential works of theology, philosophy, history and literature of the late ancient world and the early Middle Ages. Texts are made easily accessible by an index of contents in Latin and Greek language, by an index of authors, a title index and an index of subject. All of these indexes are full text ones.

The Patrologia Latina Database is an electronic version of the first edition of Jacques-Paul Migne's Patrologia Latina, published between 1844 and 1855, and the four volumes of indexes published between 1862 and 1865. Patrologia Latina comprises the works of the Church Fathers from Tertullian in 200 AD to the death of Pope Innocent III in 1216. The complete Patrologia Latina is included with all prefatory material, original texts, critical apparatus and indexes. Migne's column numbers, essential references for scholars, are included.