The HEP (high-energy physics) database, maintained by the SLAC and DESY libraries, is the granddaddy of preprint databases. Although it only claims to cover papers released since about 1974, it in fact lists some as old as 1931 (try searching on "Dirac"). The server provides a number of interfaces for searching, with a choice of output formats that includes BibTeX citation style. Even some of the oldest papers listed here are linked to lists of papers that cite them or that they cite. The database is primarily an index, but the more recent papers can be obtained in full, through links either to the Los Alamos server or to scanned images stored at the KEK library in Japan.
Begun in 1991, the Los Alamos National Laboratory's e-print server is the place to go when you see references that look like "hep-th/9701001." New users are urged to read the help pages. The server can also be accessed by e-mail: Send a message to firstname.lastname@example.org with the word "help" in the subject line. One can also sign up to receive daily e-mail that lists the new papers available in selected subjects. Authors of papers submit them directly to the server for automatic processing and indexing. The server provides abstracts in html (browsable form) and can typically supply a paper in several formats: a source file (usually a variant of TeX or LaTeX) and also postscript, dvi ("device independent") and pdf (portable document format).
The very convenient form interface allows one to browse new abstracts, browse by month and archive, search on words in the title and author fields or select a specific preprint by its number.
This link describes an October 1996 reorganization of the Los Alamos site "to facilitate growth to areas of physics not covered by the current archive structure." The server originally focused on high-energy physics and grew in an ad hoc manner, adding archives for specific subjects as required. The 1996 reorganization added a general "physics" archive, with 23 subject classes including atomic physics, biological physics, classical physics, fluid dynamics, geophysics, history of physics, instrumentation and detectors, optics, physics education, physics and society and popular physics ("covering Scientific American-level articles").
Condensed matter physics has its own archive, with seven subject classes such as materials science and superconductivity. There are four archives on mathematics, six on nonlinear sciences and one on computation and language. The high-volume archives such as high-energy physics and nuclear physics remain unchanged.
The Los Alamos server has mirror sites in France, Germany, Israel, Italy, Japan, South Korea, Taiwan and the UK. Russia, Brazil and Spain will be added soon.
The CERN preprints server provides CERN preprints and images of preprints received at CERN since 1994. Formats include postscript, pdf, tiff and gif---the last allowing most Web browsers with any graphics capability to view the papers automatically. A search engine allows searching of all the preprints on the CERN server.
The American Physical Society's e-print server, covering all areas of physics, has been on-line for about six months and currently has about 150 papers. See Physics Today, October 1996, page 63, for more information.
The "one-shot" server at the International Centre for Theoretical Physics is a prototype system designed to let one simultaneously search various other preprint servers on the Web. At present, searches are limited to a single keyword and no more than four archives at once. It is described in Computers in Physics, November/December 1996, page 520.
This is the direct line to the KEK Information Service System (KISS), which lists preprints received at KEK since 1975 and has scanned images for those in the range 1987 to 1995.
Software: Depending on your computer set-up, a preprint supplied by a server can display automatically or you may have to save the file and process it through other software. For information on software to uncompress and view files, see Los Alamos's "requisite tools" page and CERN's help page.
Compiled by Graham P. Collins