Properties of relationships and their representation
Ramez A. Elmasri, Gio C. M. Wiederhold · 1980
Data models can provide powerful abstractions to aid in the design of data structures that are relevant to database systems. A large amount of effort has been expended in the development of suitable data models. Several of these models distinguish between classes of entities and relationships among classes of entities in the abstractions they use for modelling the data. Among these models are the network model, Schmid and Swenson's model, the entity-relationship model, Navathe and Schkolnick's model, the semantic data model, and the structural model.