The creation of an information architecture is one of the identified ways that contribute to increase competitiveness, enabling cost reduction and increasing productivity in organizations. When it comes to broaden comprehensive sectors gathering several organizations (for example in the health sector), the creation of a reference architecture acquires a higher importance to guide and constrain the implementation of information architectures of the involved organizations, ensuring interoperability and alignment among them. When creating a reference architecture, following a bottom-up approach, it is essential to identify the informational entities amongst the different data models in order to be possible to integrate these informational entities in the reference architecture that is being developed. This paper describes a process which allows the verification of correspondence between informational entities amongst different data models. As far as the Portuguese case is concerned, there is just one reference architecture for the Public Administration. In this paper we describe its foundations in order to make a specialization in that architecture that can be used, further on, as a reference for the Portuguese health sector in order to increase interoperability. Nevertheless, the presented solution may also be applied to any data models integration following the bottom-up approach.