DigiZeitschriften is a digital library containing digitized back issues of core German research journals. At the moment the platform provides full-text access to more than 600 journals dating back to 1850. The archive content is edited on an ongoing basis. Any existing gaps will be filled and missing data steadily added. Users from the MPG have access to the complete journal collection, older public domain content is available free of charge to anyone.

ProQuest Dissertations and Theses Global is the world's most comprehensive collection of dissertations and theses, covering materials back to the first U.S. dissertation, accepted in 1861, as well as to European dissertations from the 17th century. The database is the official dissertations repository for the Library of Congress, with 5.5 million bibliographic citations, 3 million full texts, 4,100 contributing institutions worldwide and 250,000 works added annually. Full-text coverage spans from 1743 to the present, with citation coverage dating back to 1637.

JSTOR provides access to more than 12 million academic journal articles, books, and primary sources in 75 disciplines. Users from the Max Planck Society have access to selected archival collections of scholarly journals and more than 3,000 Open Access ebooks. The book selection is continuously extended by single e-book acquisitions by MPG libraries. For the archival collections, JSTOR's agreements with publishers include an updating provision referred to as a "moving wall". The moving wall is a fixed period of time ranging, in most cases, from two to five years, that defines the gap between the most recently published issue and the date of the most recent issues available in JSTOR.

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 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.

Since the publication of its first installment in 1976 the Theologische Realenzyklopädie has provided a comprehensive account of the state of theological research. Some 2000 articles present a multitude of historical and theological data in their context of faith and thought, theology and religion. A multidisciplinary approach integrates into the theological account not only the disciplines of Old Testament and New Testament Studies, Church History, and Systematic and Practical Theology but also Judaic Studies, Religious Studies and Philosophy.

The Web of Science™ Core Collection provides researchers with access to the world's leading bibliographic and citation databases. Authoritative, multidisciplinary content covers over 12,000 of the highest impact journals worldwide, including Open Access journals, as well as over 150,000 conference proceedings and more than 50,000 editorially selected books. You'll find current and retrospective coverage in the sciences, social sciences, arts, and humanities, with coverage back to 1900. A unique feature of the WoS is that from any bibliographic record in the database links are available to its cited references, to related articles and to citing articles. In some instances additional links (e.g. to the journal impact factor) may also be available.