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 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.

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.

Clio-online is a central Internet gateway for historical scholarship in teaching and research. Sponsored by the Deutsche Forschungsgemeinschaft (DFG), the gateway enables efficient access to the diverse range of historical online ressources available to scholars and teachers within the field of history. Clio-online ist ein zentrales Internet Fachportal zur Geschichte. Seit Mai 2002 von der Deutschen Forschungsgemeinschaft gefördert, ermöglicht das Projekt durch seine Online-Dienste und Service-Angebote einen effizienten Zugang zu den umfangreichen Online-Ressourcen innerhalb der Geschichtswissenschaften.

Welcome to CogPrints, an electronic archive for self-archive papers in any area of Psychology, neuroscience, and Linguistics, and many areas of Computer Science (e.g., artificial intelligence, robotics, vision, learning, speech, neural networks), Philosophy (e.g., mind, language, knowledge, science, logic), Biology (e.g., ethology, behavioral ecology, sociobiology, behaviour genetics, evolutionary theory), Medicine (e.g., Psychiatry, Neurology, human genetics, Imaging), Anthropology (e.g., primatology, cognitive ethnology, archeology, paleontology), as well as any other portions of the physical, social and mathematical sciences that are pertinent to the study of cognition.

The DBLP server provides bibliographic information on major computer science journals and proceedings. Initially the server was focused on DataBase systems and Logic Programming (DBLP), now it is gradually being expanded toward other fields of computer science. You may now read "DBLP" as "Digital Bibliography & Library Project". The server indexes more than 380000 articles and contains several thousand links to home pages of computer scientists (May 2003).

DART-Europe is a partnership of research libraries and library consortia who are working together to improve global access to European research theses. The Dart-Europe E-theses Portal enables access to open access research theses from nearly 600 universities in 28 European countries.

"Data Services for the Social Sciences" is a department of GESIS - Leibniz Institute for the Social Sciences. Its mission is to foster FAIR data, open science and reproducible research in the quantitative and computational social sciences. To ensure that data holdings remain usable and interpretable over the long term, it offers sustainable infrastructures and services for data management, curation, and long-term preservation. ​These include archiving services with different curation levels for different needs as well as access to archived data including access to sensitive data in the GESIS Secure Data Center. The services also cover the data registration agency da|ra and training on data management for easier retrieval and re-analysis of data.

DBIS (Datenbank-Infosystem) is a web application to find scientific databases. It includes licenced and free databases for most disciplines.

DEPATISnet is a service provided to you by the German Patent and Trade Mark Office. You can conduct online searches in patent publications from around the world stored in the database of DEPATIS, the in-house patent information system of the GPTO.

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.

EconBiz - a suject portal for economics and business studies - supports you in retrieving economic literature. It offers a literature search across important German and international databases, including the holdings of ZBW, and provides access to information services of libraries. EconBiz - die Virtuelle Fachbibliothek Wirtschaftswissenschaften - unterstützt Sie bei der Recherche wirtschaftswissenschaftlicher Fachinformationen. Sie können in Internetquellen, in Online-Katalogen und Volltexten recherchieren und auf Informationsdienstleistungen von Bibliotheken zugreifen. Enthält neben aktueller Literatur viele Publikationen , die für Wirtschaftshistoriker interessant sind (1500 ff).

EconStor is the Open Access server of the German National Library of Economics, Leibniz Information Centre for Economics. EconStor provides a basis for the free publication of academic literature in economics.

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.

EUR-Lex provides free access to public EU documents in the 24 official languages. This includes: * the Official Journal of the European Union * EU law (EU treaties, directives, regulations, decisions, consolidated legislation, etc.) * preparatory acts (legislative proposals, reports, green and white papers, etc.) * EU case-law (judgements, orders, etc.) * international agreements * EFTA documents * other public documents EUR-Lex is based on the CELEX database, and is updated daily.

The search engine provides users with the option to search various historically relevant databases and catalogues on general and European history in parallel.

The ExPASy (Expert Protein Analysis System) proteomics server from the Swiss Institute of Bioinformatics (SIB) is dedicated to molecular biology with an emphasis on data relevant to proteins. It allows you to browse through a number of databases produced in Geneva, such as Swiss-Prot, PROSITE, SWISS-2DPAGE, SWISS-3DIMAGE, ENZYME, as well as other cross-referenced databases (such as EMBL/GenBank/DDBJ, OMIM, Medline, FlyBase, ProDom, SGD, SubtiList, etc). It also allows access to many analytical tools for the identification of proteins, the analysis of their sequence and the prediction of their tertiary structure. ExPASy also offers you many documents relevant to these field of research and you will find from the servers, links to most relevant sources of information across the Web. Swiss-2DService is a non-profit 2-D PAGE service to the scientific community. ExPASy was created in August 1993, it was one of the first WWW servers for biological sciences. Since that date it has undergone constant modifications and improvements.

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.