BASE is a multidisciplinary search engine for scholarly internet resources which have been harvested from several hundred scientific repositories. Some of the indexed resources in BASE are subject to license, while most material is free available ("open access").

The Staatsbibliothek zu Berlin - Preußischer Kulturbesitz (Berlin State Library - Prussian Cultural Heritage) acquires texts from all fields of knowledge in all languages, in every available form, from all epochs and all countries of the world - providing the materials are of interest for academic and research purposes. Current holdings and collections include printed works from many centuries, manuscripts, music autographs, maps, globes, atlases, newspapers and periodicals, various microformed materials, an increasing number of digitally presented texts as well as extensive databases.

Die Bibliographie des Musikschrifttums online ist eine internationale, interaktive und frei nutzbare Bibliographie für die Musikwissenschaft. Sie dient als Fortsetzung des bis zum Berichtsjahr 1988 gedruckt erschienenen Werkes.

The Bibliography of the History of Art (BHA) contains abstracts and indexes of current publications in the history of art, including scholarly journals, conferences, book, exhibition reviews, and exhibition catalogues. The records consist of bibliographic citations, abstracts, and indexing. Note that the database search includes BHA, covering 1990-2007, the International Bibliography of Art (IBA), covering the years 2008 and part of 2009, and the Répertoire de la litterature de l'art (RILA), one of the predecessors of BHA, with records that cover 1975–1989.

With more than 700.000 items, the BBF is today Europe's second largest library specialised in education. Like the Herzog-August-Bibliothek in Wolfenbüttel, it belongs to the association of German cultural research libraries fulfilling a national role.

BioMed Central is an STM (Science, Technology and Medicine) publisher of 270 peer-reviewed open access journals. The portfolio of journals spans all areas of biology, biomedicine and medicine and includes broad interest titles, such as BMC Biology and BMC Medicine alongside specialist journals, such as Retrovirology and BMC Genomics. The Max Planck Society is a BMC member and covers article-processing charges for Max Planck authors centrally. Further details are available on the MPDL website.

BN-OPALE PLUS combines into one catalog the records for the printed, sound, audiovisual, and multimedia materials collected by the Bibliothèque nationale de France (BnF) from its beginnings to the present day. The BN-OPALE PLUS catalog contains records for: * Books and periodicals making up the heritage collections, stored in BnF's François-Mitterrand Library, * Microfiche and microfilm, mostly created from heritage materials, * A selection of books and periodicals from special departments, * Open-Access materials from all the BnF libraries, * Sound recordings, videos, multimedia, and electronic materials comprising the heritage collections * Printed material and periodicals digitized by BnF, mostly in image format, * Electronic periodicals of which BnF also has the printed version, * Still images digitized by BnF, * Special materials regarding performing arts (pamphlets, programs, manuscripts,...) and cinema (movie posters, photographs). In addition, this catalog offers authority records containing extensive information on access rights (intellectual property rights and copyrights, subject matter, certificates, brand names, and others).

The union catalog encompasses the holdings of the Bavarian State Library, of libraries of Bavarian Universities and Universities of Applied Sciences, of several regional libraries and of some institutions affiliated with churches or ministeries. Die Verbunddatenbank umfasst den Bestand der Bayerischen Staatsbibliothek, der Universitäts- und Fachhochschulbibliotheken, diverser staatlicher Regionalbibliotheken und einiger kirchlichen und ministeriellen Einrichtungen.

Cairn offers the most comprehensive collection of French and Belgian journals in social sciences available online. Note that access to newer content is generally not free of charge (moving wall 2 to 5 years).

This catalogue records information in e-journals, e-books, databases, and printed material about themes in the field of the international law. Especially, a large part of the print collection of the Peace Palace Library is searchable through this catalogue. This collection consists of books and materials since 1913.

CiteSeer is a scientific literature digital library and search engine that focuses primarily on the literature in computer and information science. CiteSeer aims to improve the dissemination and feedback of the scientific literature and to provide improvements in functionality, usability, availability, cost, comprehensiveness, efficiency, and timeliness in the access of scientific and scholarly knowledge.

Cogitatio is an academic and community-oriented publisher based in Lisbon, which was founded in 2014 with the aim of promoting the open access dissemination of scientific knowledge. Cogitatio currently publishes 4 peer-reviewed Open Access journals focusing on research in the social sciences and humanities. From January 1, 2023, the Max Planck Society covers article-processing charges for Max Planck authors centrally. Further details are available on the MPDL website.

Copac exposes rare and unique research material by bringing together the catalogues of c.90 major UK and Irish libraries. In a single search you can discover the holdings of the UK’s national libraries (including the British Library), many University libraries, and specialist research libraries.

Copernicus Publications has been publishing highly reputable peer-reviewed open access journals since 2001. Through interactive, multi-stage open access publishing, Copernicus aims to bring real transparency into scientific quality assurance. The Max Planck Society covers article-processing charges for Max Planck authors centrally. Further details are available on the MPDL website.

The catalog comprises the holdings of the locations Leipzig since 1913, Frankfurt am Main since 1945, the holdings of the Deutsches Musikarchiv since 1976, and archival papers of the Deutsches Exilarchiv 1933-1945 since 2005. The catalog covers monographs, journals, maps and atlases, music and sound storage media, and dissertations published in Germany since 1913 (in print or electronically), in addition, translations from German into other languages and foreign-language works related to Germanic culture (since 1941). -- Der Katalog umfasst die Bestände der Standorte Leipzig seit 1913, Frankfurt am Main seit 1945, die Bestände des Deutschen Musikarchivs seit 1976 und die Archivalien des Deutschen Exilarchivs 1933-1945 seit 2005. Der Katalog beinhaltet in Deutschland seit 1913 erschienene Monografien, Zeitschriften, Karten und Atlanten, Musikalien und Tonträger, Dissertationen und Habilitationsschriften in gedruckter oder elektronischer Form, außerdem Übersetzungen aus dem Deutschen in andere Sprachen und fremdsprachige Germanica (seit 1941).

The Digital Library of the Commons (DLC) is a gateway to the international literature on the commons. The DLC provides free and open access to full-text articles, papers, and dissertations. This site contains an author-submission portal; an Image Database; the Comprehensive Bibliography of the Commons; a Keyword Thesaurus, and links to relevant reference sources on the study of the commons.

Dimensions is a linked research knowledge system that re-imagines discovery and access to research. Developed by Digital Science in collaboration with over 100 leading research organizations around the world, Dimensions brings together grants, publications, citations, alternative metrics, clinical trials, patents and policy documents to deliver a platform that enables users to find and access the most relevant information faster, analyze the academic and broader outcomes of research, and gather insights to inform future strategy.

The DOAJ service lists toll-free, quality controlled, scientific and scholarly journals. It generally aims at covering all subjects and languages. The DOAJ Articles Search is restricted to those journals the publisher has supplied article metadata for.

The EZB is a huge directory of electronic journals which mirrors the central Max Planck Society subscriptions as well as the local licensing situation of the institutes. Access rights to the contents of the individual journals are indicated with "traffic lights". Entries are searchable on journal level.