revised and expanded version based on recent experience UNESCO text fr Paris Unesco [1977?] 1977 monographic eng 79 p. The need for information obtained and processed by scientific methods is now becoming evident in various forms ans its growth is one of the outstanding features of recent years. (Font: Introducció) Dossier documental ES-BaOER 130626 20180914100143.0 vtls000000471 cat