IRS13 Scientific Report No. IRS-13 Information Storage and Retrieval Thesaurus, Phrase and Hierarchy Dictionaries chapter E. M. Keen Harvard University Gerard Salton Use, reproduction, or publication, in whole or in part, is permitted for any purpose of the United States Government. VI 1-9 Collection and Number of Dictionary Phrases IRE-3 Thesaurus-2 93 IRE-3 Thesaurus-3 374 CRAN-2 Thesaurus-3 309 ADI Thesaurus-i 247 Data on Phrase Dictionaries Fiq. 4