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.

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).

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.

CORE’s mission is to aggregate all open access research outputs from repositories and journals worldwide and make them available to the public. In this way CORE facilitates free unrestricted access to research for all. We offer seamless access to millions of open access research papers, enrich the collected data for text-mining and provide unique services to the research community. CORE is providing a free API.

Data Europa EU is a central point of access to European open data from international, European Union, national, regional, local and geodata portals. The official portal for Euopean data consolidates the former EU Open Data Portal and the European Data Portal. Data Europa EU gives access and fosters the reuse of European open data among citizens, business and organisations. The portal promotes and supports the release of more and better-quality metadata and data by the EU’s institutions, agencies and other bodies, and European countries, enhancing the transparency of European administrations. Furthermore, it is intended to educate citizens and organisations about the opportunities that arise from the availability of open data. Currently, Data Europa EU contains more than 1.5 million European public sector datasets grouped by over 180 catalogues and pertaining to different topical categories.

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).

GBV is the Common Library Network of the German Federal States Bremen, Hamburg, Mecklenburg-Vorpommern, Niedersachsen, Sachsen-Anhalt, Schleswig-Holstein and Thüringen. The head office of the GBV (VZG) is situated in Göttingen. The GBV has established a virtual library in form of the GBV Union Catalogue (GVK) combining the resources of all participating libraries and making them easily accessible to the public.

The union catalog lists the holdings of all scientific libraries in Hessen and Rheinhessen. Inter-library loan requests may be submitted.

The Internet Archive is a non-profit organization that offers permanent access for the general public to historical collections that exist in digital format. The Internet Archive includes collections of digitized materials, including websites, software applications and games, music, movies and videos, moving images, and nearly three million public-domain books. The Internet Archive allows the public to upload and download digital material , but most of its data is collected automatically by its web crawlers to preserve as much of the public web as possible. The Wayback Machine, a huge web archive, contains over 150 billion web captures.

The KOBV-Index is a central database that is maintained and regularly updated at KOBV-Zentrale. Der KOBV-Index ist eine zentrale Datenbank, die in der KOBV-Zentrale gepflegt und regelmäßig aktualisiert wird.

The Library of Congress Online Catalog is a database of books, serials, computer files, manuscripts, cartographic materials, music, sound recordings, and visual materials in the Library's collections.

LIVIVO bundles scientifically relevant resources from the subjects fields medicine, health, nutrition, environmental and agricultural sciences. It provides a common search interface over various data sources, such as library catalogs, specialist bibliographic databases, full texts from journals, and quality-controlled web content. LIVIVO combines the former ZB MED search portals MEDPILOT (2003 to 2015) and GREENPILOT (2009 to 2015).

MIA contains the writings of 592 authors representing a complete spectrum of political, philosophical, and scientific thought, generally spanning the past 200 years. Being a communist means working for the self-emancipation of the working class; it means striving to unite the working class, in all its diversity, in the struggle to overthrow capitalism. In the 1840s, Marx and Engels placed communism on a scientific footing through the theory of dialectical materialism. Marxists are those who have continued this ever since. If any one of the following criteria apply, the MIA Collective may decide to place the writer into the Reference Archive: (i) they pre-date Marx and Engels, (ii) they specifically reject Marxism, (iii) their work is practically and theoretically unconnected or hostile toward the workers movement, (iv) their work is idealistic or lacking in dialectic. Where a writer contributes to Marxist theory and practice for a part of their life, while other works lie outside of Marxism, then the whole of their writing will be placed in the Marxist Writers' Archive.Contains: Karl Marx/ Friedrich Engels - Werke ; Rosa Luxenburg; August Bebel; Antonio Gramsci ...

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

The BSZ develops and maintains the SWB database in cooperation with 1,200 libraries in Baden-Württemberg, Pfalz, Saarland and Sachsen. The online catalog offers bibliographic data free of charge: Monographs, periodicals, articles, loose-leaf collections, off-prints, conference proceedings, university publications, reviews, abstracts, tables of contents, maps, music, audiovisual material, microforms, electronic resources (data media), online resources; scientific and popular literature from all subjects and in all languages from the 15th century to the present; scientific literature (according to the DFG special subject fields programme) from theology, ancient orient, art, music, archeology, law and criminology;