arXiv is an e-print service in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance, statistics, electrical engineering and systems science, and economics. It provides access to more the 1.3 million e-prints. The Max Planck Society is a member institution of arXiv.

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.

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).

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.

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.

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).

The primary aim of DOAB is to increase discoverability of Open Access books. Academic publishers are invited to provide metadata of their Open Access books to DOAB. An overview of participating publisher can be found here.

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.

Edition Open Access provides open access to the publications of the Max Planck Research Library for the History and Development of Knowledge. The aim is to disseminate the results of scholarly work – in accordance with the open-access paradigm – to a broad audience rapidly and at low cost. The volumes presented here are directed at scholars and students in a wide range of disciplines. The works are available online both as print-on-demand books and open-access publications and can be accessed, together with additional information.

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.

Throughout Europe, national patent offices and the European Patent Office (EPO) offer free patent information on the Internet Patents reveal solutions to technical problems, and they represent an inexhaustable source of information: more than 80 percent of man's technical knowledge is described in patent literature. From the middle of 1998 onwards, esp@cenet users have been able to access the bibliographic data of all patents published in the preceding two years by any member state of the European Patent Organisation, as well as by the European Patent Office and the World Intellectual Property Organization (WIPO). In addition, full-page facsimile images of documents are also retrievable to facilitate more detailed analysis of these documents. The data for this particular service is stored at the relevant national office.

F1000 Research is an open research and open access publishing platform, providing a suite of publishing services directly to researchers, research funders and institutions. The platform supports innovative features such as post-publication peer review, open peer review, and publication of negative results. The Max Planck Society covers article-processing charges for the open access journal F1000Research centrally. Further details are available on the MPDL website.

Frontiers is a community-oriented open-access academic publisher and research network. It was launched in 2007 by scientists from the Swiss Federal Institute of Technology in Lausanne and aims to provide better tools and services to researchers in the Internet age. Since then, Frontiers has become one of the fastest-growing open-access scholarly publishers: over 400,000 high-quality, peer-reviewed articles have been published in about 200 community-driven journals across more than 300 specialty niches in science, medicine and technology. The Max Planck Society covers article-processing charges for Max Planck authors centrally. Further details are available on the MPDL website.

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.

Google Book Search is a service from Google that searches the full text of books that Google scans, converts to text using optical character recognition, and stores in its digital database.

H1 Connect is a literature awareness and recommendation tool that comprehensively highlights and reviews the most interesting papers published in biology and medicine. It is based on the recommendations of a faculty of selected leading scientists and enables researchers to set up a personalized literature service.