 select dissemin inform the contribut duplic previou studi complement earlier public close gap exist literatur prior 1966 1971 addition bold attempt evalu critic object histori mechan select dissemin sdi reflect literatur initi descript luhn 1958 1961b post-1970 period sdi boom began lose ground popular on-line interact system the review question interpret concept sdi implement evolut light work perform compani govern agenc univers societi librari fourteen year 