Manipulation of Trees in Information Retrieval* CACM February, 1962 Salton, G. CA620209 JB March 20, 1978 3:44 PM 1087 4 634 634 4 634 931 5 634 1324 5 634 329 5 634 634 5 634 634 5 634 634 5 634 202 6 634 396 6 634 634 6 634 634 6 634 652 6 634 653 6 634