1. Alpha: An extension of relational algebra to express a class of recursive queries;Agrawal,1987
2. Efficient management of transitive relationship in large data and knowledge bases;Agrawal,1989
3. Efficient implementation of lattice operations;Ait-Kaci;ACM Trans. Prog. Lang. Systems,1989
4. Partial match retrieval in implicit data structures;Alt;Inform. Process. Lett.,1984
5. Representation of lattices by sets;Birkhoff;Trans. AMS,1948