Fig. 5
![Fig. 5](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs12889-020-09368-z/MediaObjects/12889_2020_9368_Fig5_HTML.png)
Network visualization map of research themes through mapping of most frequent terms in titles/abstracts of the retrieved documents. A minimum threshold of 50 occurrences was used
Network visualization map of research themes through mapping of most frequent terms in titles/abstracts of the retrieved documents. A minimum threshold of 50 occurrences was used