V. S. Lakshmanan. Query Evaluation with Null Values: How Complex is Completeness?. In C. E. Veni Madhavan, editor, Foundations of Software Technology and Theoretical Computer Science, Ninth Conference, Bangalore, India, December 19-21, 1989, Proceedings. Volume 405 of Lecture Notes in Computer Science, pages 204-222, Springer, 1989.
Abstract is missing.