International scientometric databases, repositories and search engines

Google Scholar (USA) -  a public search engine, that indexes metadata of scientific publications on all branches of knowledge, published in a variety of formats. Google Scholar index contains the majority of peer-reviewed journals of largest scientific publishers in Europe and America. This product has the tools for tracking citation indexed of scientific publications. Although Google has not officially disclose the amount of Google Scholar index, experts estimate this volume at approximately 160 million documents.

 Ulrichsweb (Ulrich’s Periodicals Directory) —  an authoritative international database, which contains a description of over 300,000 periodicals, and is also actively used by employees of electronic catalogs, libraries, repositories, scientometric bases Scopus and Web of Science for detailed information about scientific journals.

Crossref – an association of publishers of scientific publications (magazines, monographs, collections of conferences materials), created with the aim of developing and supporting the world-wide high-tech infrastructure of scientific communications. The main task of CrossRef is to promote the widespread use of innovative technologies to accelerate and facilitate research. All articles are assigned a DOI with a prefix 10.31498.

Index Copernicus (Poland) – scientometric database, established in 1999 in Poland. The database has a number of tools for performance evaluation, which allow you to track and establish the importance of scientific publications, the contribution of scientists and research institutions. Index Copernicus also carries the traditional abstracting and indexing of publications.

OCLC WorldCat (Ohio College Library Center) - a global union catalog and the world's largest bibliographic database that itemizes the collections of 72,000 libraries in 170 countries that participate in the Online Computer Library Center (OCLC) global cooperative. It contains more than 330 million records, representing over 2 billion physical and digital assets (articles, archival materials, books, journals, maps, music, videos, and other resources) in 485 languages.

Open Access Infrastructure for Research in Europe (OpenAIRE) is a project developed under the European Commission's open access policy and aims to support research infrastructure to fulfill the European Union's open access mandate. This repository covers sources of information in all fields of knowledge and has a volume of more than 11.5 million scientific publications (journal articles, dissertations, books, lectures, reports, etc.) obtained from 610 repositories of institutions from 52 countries.

BASE (Bielefeld Academic Search Engine) - one of the world's most voluminous multi-disciplinary search engines especially for academic open access web resources. This engine collects, normalises, and indexes data using the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH). BASE provides more than 70 million documents from more than 3,000 sources. Where available, bibliographic data is provided, and the results may be sorted by multiple fields, such as by author, Dewey Decimal Classification or year of publication.

ResearchBib (Japan) - international multidisciplinary base of scientific journals, which includes more than 8,000 titles from around the world. It provides service indexing journals listed in its database, which in turn contributes to the development of the indexed journal.

Open Ukrainian Citation Index (OUCI) is a search engine and database of scientific citations that come from all publications that use the Cited-by service from Crossref and support the Initiative for Open Citations. OUCI is designed to simplify the search for scientific publications, to draw the attention of editors to the problem of the completeness and quality of metadata of Ukrainian scientific publications, to improve the presentation of Ukrainian scientific publications in specialized search engines (for example, Dimensions, Lens.org, 1findr, Scilit), which can expand their readership, will allow bibliometricians to freely study the connections between authors and documents from various scientific disciplines, in particular, in the field of social sciences and humanities.

ROAD is a service offered by the ISSN International Centre with the support of the Communication and Information Sector of UNESCO. Launched in December 2013, ROAD provides a free access to those ISSN bibliographic records which describe scholarly resources in Open Access: journals, monographic series, conference proceedings, academic repositories and scholarly blogs. These records, created by the ISSN Network (89 National Centres worldwide + the International Centre), are enriched by information extracted from indexing and abstracting databases, directories (DOAJ, Latindex, The Keepers registry) and journals indicators (Scopus). ROAD is in line with the actions of UNESCO for promoting Open Access to scientific resources. ROAD is complementary to the Global Open Access Portal (GOAP) developed by UNESCO and providing a snapshot of the status of Open Access to scientific information around the world.

 Vernadsky National Library of Ukraine (Ukraine) — the largest by volume and floor space Ukrainian Library, the main scientific research center in the country, Scientific Research Institute of the History Department, Philosophy and Law of National Academy of Sciences of Ukraine. Included in the twenty largest national libraries in the world.

Polish Scholarly Bibliography (PBN) (Poland) - portal of the Ministry of Science and Higher Education of Poland, which contains information about scientific publications in scientific journals around the world. It is part of POL-on (Information on higher education system).

Abstracts Database "Ukraїnіka Naukova" (Ukraine) - Ukrainian nationwide abstract database data on natural, technical, social, humanitarian and medical sciences. It founded by the Vernadsky National Library of Ukraine and the Institute for Information Recording of NAS of Ukraine.

 Ukrainian abstract journal "Dzherelo" - periodic information publication for displaying the content of scientific publications are printed in Ukraine on natural, technical, social and humanitarian disciplines.