Michael K. Buckland Anthony Hindle Gregory P. M. Walker Methodological problems in assessing the overlap between bibliographical files and library holdings. 89-105 1975 11 Inf. Process. Manage. 3-4 http://dx.doi.org/10.1016/0306-4573(75)90011-4 db/journals/ipm/ipm11.html#BucklandHW75