title: banks : browsing and keyword searching in relational databases. authors: b aditya , g bhalotia , s chakrabarti , a hulgeri , c nakhe , p parag , s sudarshan. venue: vldb. year: 2002
title: missing information ( applicable and inapplicable ) in relational databases. authors: ef codd. venue: acm sigmod record ,. year: 1986.0