Freely available and open access sources

• Google Scholar - search records and full text of study materials across multiple disciplines
• OpenAIRE - platform for open publishing of documents and scientific data generated within the European Commission's 7th Framework Programme for Research

Journals

• Open Access Journal Search Engine - directory of OA journals with search option
• Directory of Open Access Journals - databasis of OA journals, you can search by journal or article title
• Open Access Journals - OA journals search engine from Google

Repositories and digital libraries

• The Directory of Open Access Repositories  - directory of institutional repositories with freely available content from all over the world
• Repository66 - map of institutional repositories around the world with freely available content.
• Registry of Open Access Repositories - search records from institutional and disciplinary repositories
• Národní úložiště šedé literatury - technically oriented sources from Czech Republic, especially from Czech universities and the Academy of Science
• arXiv - disciplinary repository for mathematics, physics, technology and engineering; has over 700,000 documents
• RePEc  - digital library maintained by volunteers that is focused on economics
• Digital Mathematic Library - a collection of freely available documents from Czech Republic focused on mathematics; offers both record and full text
• GitHub - source codes repository

Books

• Directory of Open Access Books - books published by academic publishers
• Google Books - database of books from all over the world including not only records, but often also full text

Catalogues a information gateways - bibliographic references searching

• Uniform information gateway - interface for various Czech and foreign sources (list of sources)
• Technic gateway - part of UIG focused on technical disciplines
• Union catalogue of the Czech Republic CASLIN - platform for searching documents in Czech libraries from one place
• Czech national bibliography CNB - records of documents published in Czech republic
• Articles in czech newspapers, magazines a collections
• Worldcat - world biggest bibliographic database, searching catalogues of more than 70 thousands libraries

Norms, patents

• Czech Office for Standards, Metrology and Testing
• Industrial Property Office
• US Patent and Trademark Office
• esp@cenet - service for patent searching (focused on Europe)