Vannevar Bush's famous paper "As We May Think" (1945) described an imaginary information retrieval machine, the Memex. The Memex is usually viewed, unhistorically, in relation to subsequent developments using digital computers. This paper attempts to reconstruct the little-known background of information retrieval in and before 1939 when "As We May Think" was originally written. The Memex was based on Bush's work during 1938-1940 developing an improved photoelectric microfilm selector, an electronic retrieval technology pioneered by Emanuel Goldberg of Zeiss Ikon, Dresden, in the 1920s. Visionary statements by Paul Otlet (1934) and Walter Schuermeyer (1935) and the development of electronic document retrieval technology before Bush are examined.

Michael Buckland's notes on Emanuel Goldberg, with links to other resources.

"Emanuel Goldberg (Portrait) was born in Moscow, Russia, in 1881, a chemist, inventor, and industrialist who contributed to almost all aspects of imaging technology in the first half of the twentieth century: photographic sensitometry, reprographics, standardized film speeds, color printing (moiré effect), aerial photography, extreme microphotography (microdots), optics, camera design (the Contax), the important, early hand-held Kinamo movie camera, and early television technology. He received his doctorate from Wilhelm Ostwald's institute in Leipzig in 1906."

Haystack provides modular search for Django. It features a unified, familiar API that allows you to plug in different search backends (such as Solr, Whoosh, etc.) without having to modify your code.

A standalone search engine, meant to provide fast, size-efficient and relevant fulltext search functions to other applications. Sphinx was specially designed to integrate well with SQL databases and scripting languages.

The classes, structs, unions and interfaces with brief descriptions.

PyLucene is a Python extension for accessing Java Lucene. Its goal is to allow you to use Lucene's text indexing and searching capabilities from Python.

Zebra is a high-performance, general-purpose structured text indexing and retrieval engine.

Djapian provides integration between Xapian and Django.

Xapian is an Open Source Search Engine Library, released under the GPL. It's written in C++, with bindings to allow use from Perl, Python, PHP, Java, Tcl, C# and Ruby.

CLucene is a high-performance, scalable, cross platform, full-featured, open-source indexing and searching API. It is written in C++.

Cheshire3 is a fast XML search engine, written in Python for extensability and using C libraries for speed.

Solr is an open source enterprise search server based on the Lucene Java search library, with XML/HTTP and JSON APIs, hit highlighting, faceted search, caching, replication, and a web admin interface.