1. C. Batini, M. Lenzerini, and S. Navathe. A comparitive analysis of methodologies for database schema integration. ACM Computing Surveys, 18(4):323–364, 1986.
2. B. Cadish and Z. Diskin. Algebraic graph-based approach to management of multibase systems, I: Schema integration via sketches and equations. In Next Generation of Info-technologies and Systems, NGITS'95, 2nd Int.Workshop (Israel), 1995.
3. U. Dayal and II. Hwang. View definition and generalization for database integration of a multibase system. IEEE Trans. Software Eng., 10(6):628–644, 1984.
4. Z. Diskin. Mathematical aspects of schema integration. TR-9502, Frame Inform Systems, Riga, 1995. (On ftp: //ftp.cs.chalmers.se/pub/users/diskin/tr9502.*).
5. Z. Diskin. Formalizing graphical schemas for conceptual modeling: Sketch-based logic vs. heuristic pictures. TR-9501, Frame Inform Systems, Riga, 1995.