On Relational Algebra with Marked Nulls.

The theory of relational databases

1983 • 1,371 citations

Incomplete Information in Relational Databases

1984 • 1,051 citations

On the foundations of the universal relation model

1984 • 294 citations

A sound and sometimes complete query evaluation algorithm for relational databases with null values

1986 • 154 citations

On representing incomplete information in a relational data base

1981 • 61 citations

Incomplete information and dependencies in relational databases

1983 • 45 citations