Researchr is a web site for finding, collecting, sharing, and reviewing scientific publications, for researchers by researchers.
Sign up for an account to create a profile with publication list, tag and review your related work, and share bibliographies with your co-authors.
Gultekin Özsoyoglu, Z. Meral Özsoyoglu, Victor Matos. Extending Relational Algebra and Relational Calculus with Set-Valued Attributes and Aggregate Functions. ACM Trans. Database Syst., 12(4):566-592, 1987. [doi]
Abstract is missing.