id	author	title	date	pages	extension	mime	words	sentence	flesch	summary	cache	txt
iassist-898		iassist-898		13	.pdf	application/pdf	6644	399	51	In case a user searches for a specific study and does not know which terms to state, it is necessary to link DDI concepts to external thesaurus concepts. DDI concepts are organized in so-called concept schemes which are similar to thesauri or classification systems regarding structure and content.	cache/iassist-898.pdf	txt/iassist-898.txt