Probabilistic models of indexing and searching

for example, Robertson and Sparck Jones, 1976; van Rijsbergen, 1977; Harper and van Rijsbergen, 1978), and the work done in the USA on automatic indexing using within-document frequencies of terms (notably by Bookstein and Swanson, 1974, 1975; Harter, 1975a, b; Bookstein and Kraft, 1977). (There is a considerable body of related work by Salton, Yu and associates