The requirements of information retrieval, of finding information whose location or very existence is a priori unknown. Calvin Mooers (1947)
An information retrieval system will tend not to be used whenever it is more painful and troublesome for a customer to have information than for him not to have it... Where an information retrieval system tends not to be used, a more capable information retrieval system may tend to be used even less. Calvin Mooers (1959)