Computer Sciences

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O'Reilly Online Learning (formerly Safari)
This subscription package to over 35,000 ebooks and 6,000 videos includes primarily computer science, but with many engineering and business books too. It also includes hundreds of interactive tutorials and an AI-like "answers" feature for technical questions.
Gale OneFile: Computer Science

Access leading business and technical publications in the computer, telecommunications, and electronics industries.

ACM Digital Library (Association for Computing Machinery)

Association of Computing Machinery (ACM)'s complete collection of publications, including Journals, Transactions, Magazines, Proceedings, and ACM Books. Also includes the "ACM Guide to Computing Literature", a comprehensive database of citation information on the field of computing.

Semantic Scholar

Semantic Scholar is a free database of millions of scholarly publications in the fields of computer science and neuroscience. Most of the indexed content is open access, although some content may require use of Interlibrary Loan to get the full text.

As a joint project of Microsoft, Google, and Baidu, it offers a significantly more sophisticated search engine than Google Scholar for these fields including advanced filters designed specifically for those knowledge domains.

DOAJ : Directory of Open Access Journals
A service that provides access to quality controlled scientific and scholarly Open Access Journals.