<P> In the UK, the National Archives provides a consolidated search of its own catalogue and a wide variety of other archives listed on the Access to Archives index . Digital copies of various classes of documents at the National Archives (including wills) are available from DocumentsOnline . Most of the available documents relate to England and Wales . Some digital copies of primary sources are available from the National Archives of Scotland . Many County Record Offices collections are included in Access to Archives, while others have their own on - line catalogues . Many County Record Offices will supply digital copies of documents . </P> <P> In other regions, Europeana has digitized materials from across Europe while the World Digital Library and Flickr Commons have items from all over the world . Trove has primary sources from Australia . </P> <P> Most primary source materials are not digitized and may only be represented online with a record or finding aid . Both digitized and not digitized materials can be found through catalogs such as WorldCat, the Library of Congress catalog, the National Archives catalog, and so on . </P> <P> History as an academic discipline is based on primary sources, as evaluated by the community of scholars, who report their findings in books, articles and papers . Arthur Marwick says "Primary sources are absolutely fundamental to history ." Ideally, a historian will use all available primary sources that were created by the people involved at the time being studied . In practice some sources have been destroyed, while others are not available for research . Perhaps the only eyewitness reports of an event may be memoirs, autobiographies, or oral interviews taken years later . Sometimes the only evidence relating to an event or person in the distant past was written or copied decades or centuries later . Manuscripts that are sources for classical texts can be copies of documents, or fragments of copies of documents . This is a common problem in classical studies, where sometimes only a summary of a book or letter has survived . Potential difficulties with primary sources have the result that history is usually taught in schools using secondary sources . </P>

State the importance of printed books as a source of the history of modern india