Reference type identification

References type identification: M-- ordinary books, C-- conference proceedings, G-- compilation, N-- newspaper, J-- periodicals, dissertations D--, R-- report, S-- standard, P- - patents, DB-- database, [DB / OL] - online internet database, [DB / MT] - tape database, [M / CD] - CD books, [CP / DK] - disk software, [ J / OL] - online journals, [EB / OL] - online bulletin