North American Immigrant Letters, Diaries and Oral Histories includes thousands of authors and approximately 100,000 pages of information, thus providing a unique and personal view of what it meant to immigrate to America and Canada between 1800 and 1950. Composed of contemporaneous letters and diaries, oral histories, interviews, and other personal narratives, the series provides a rich source for scholars in a wide range of disciplines. In selected cases, users will be able to hear the actual audio voices of the immigrants.

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.

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.

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).

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).

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.

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.

Periodicals Archive Online is a major archive that makes the backfiles of scholarly periodicals in the arts, humanities and social sciences available electronically, providing access to the searchable full text of hundreds of titles. The database spans more than two centuries of content, 37 key subject areas, and multiple languages.

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.

The database comprises numerous important periodicals published since 1997 in the Baltic States (Estonia, Latvia, Lithuania), Belarus, Moldova and Ukraine. It includes journals as well as neswpapers which are mostly in Russian and cover various issues of domestic and international importance.

The Miras Maktoob collection of Persian e-books consists of 249 volumes (189 works) originally published by the Written Heritage Research Institute (Miras Maktoob), a non-governmental organization in Tehran. These e-books contain both Persian and Arabic works on Islamic history and culture in the broadest sense.

The "JPS Journals" platform provides access to the academic journals published by the Physical Society of Japan (JPS). These journals cover the subject area from condensed matter physics to particle physics.

The Portico digital preservation service was created in 2002 with the support of libraries and publishers to ensure that the world's scholarship, now stored and disseminated largely in digital form, will be accessible to future generations. Users from the Max Planck Society gain access to preserved content when specific conditions or “trigger events” cause titles to no longer be available from the publisher or through a successor.