3.7 Let us sum up
Evidences of organizing and archiving written form of information is dated back to around 3000 BC during Sumerian civilization but modern IRR is greatly influenced by the great visionary Vanneuvar Bush. In 1945 he envisioned a single window user interface for fast access to the contents of the world's libraries by 2010 and reported in his seminal article. Information retrieval deals with the problems related with the storage, access and searching of information sources by persons in need of information. In this digital network era, information sources are growing at an exorbitant rate, available in many forms and formats, and accessible through various channels. Moreover, recent advancements in ICT help in integration of different information sources and process them on a larger scale. OA retrieval systems, as part of the great landscape of IRR are promising a new era of content retrieval. This unit on OA retrieval is an attempt to provide systematic exposition of OA retrieval system from traditional to modern era with facets on techniques, approaches, models and evaluation processes of retrieval systems. It briefly discusses features of major OA retrieval systems at global scale including many ongoing experiments on OA retrieval like map-view of results, integration of controlled vocabularies, subject categories and ontology-driven organization. It dedicates a complete section on text retrieval engines as most of the OA contents providers and OA content management software are increasingly using open source text retrieval engines for dissemination of OA resources. This unit also deals with multilingual OA content retrieval in relation with necessary configuration of OA repository management software.