Fig. 2
From: Interoperability of heterogeneous health information systems: a systematic literature review
A The frequency of selected health information systems interoperability articles from databases based on years. B The growth trend of articles in the field of interoperability in databases. C Geographical scope in the subject of interoperability in the world based on the google search (https://trends.google.com). D The comparison of the google search trend of interoperability and health information systems interoperability (https://trends.google.com)