Mathematics  

MathSciNet is an electronic publication offering access to a database of reviews, abstracts and bibliographic information for much of the mathematical sciences literature. It contains over 2 million items and over 1 million direct links to original articles. It is an electronic version of Mathematical Reviews which began publication in 1940. It uses the Mathematics Subject Classification to categorize materials by subject.

ZentralBlatt Math is an alternative database giving online access to publications in the field of mathematics. In many ways it is similar to MathSciNet. It uses the Mathematics Subject Classification , and is searchable by author, title, MSC subject category, review text, etc. For an exhaustive search of a particular topic, one would be advised to search both the ZentralBlatt Math and the MathSciNet databases.

ERIC is the database giving access to literature in the field of education. This database should be used for mathematics education. Many of the journal articles and Eric Documents accessed in ERIC cannot be found in either MathSciNet or ZentralBlatt Math.

Compendex is a database for the engineering sciences. It is an extremely large database and offers many options for controlling and narrowing the search for bibliographic information. It is particularly useful for applied mathematics, but it also frequently posts journal articles in pure mathematics which were published in engineering journals.

The ACM Guide is a point of access to the computer science literature. It includes full text for all Association of Computing Machinery [ACM] Publications. Computing Reviews is also accessed through this portal. CR gives access to other journals and books.

The Current Index to Statistics indexes the statistical literature found in 160 core journals plus books and selected journals in cognate fields. Indexing goes back to 1975.

Cryptology ePrint Archive covers the rather specialized field of digital encryption. Much of the material is applied mathematics with an application to computer science.

The Front for the Mathematics ArXiv has preprints not only for mathematics, but also includes statistics, quantitative biology, quantitative finance, behavioral science, etc.

MathNet preprints indexes other preprint sites. These are mostly preprint sites in Europe. Unfortunately the links are sometimes broken.

This is an excellent source for technical reports. It provides links to hundreds of agencies, both in the United States and abroad, which produce in-house technical literature. One good example would be the CERN archives.