Coverage by Geographical Area
There are indexing and abstracting services with coverage limited to literature of a particular country. Various countries bring out national I & A services with a view to achieve bibliographical control of domestic literature and to disseminate them. As it is difficult to have comprehensive coverage of all subjects in one, there are subject specialised services with coverage limited to a particular country.
I & A services are also devoted to particular kind of documents of a country National I and A Services in various subjects.