Fig. 1
From: Reflecting trends in the academic landscape of sustainable energy using probabilistic topic modeling
a Cumulative number of Scopus-indexed journal articles per year, which contain the search terms sustainab* and energy; records before 1990 are just shown as supplementary information and have not been included in any of the modeling procedures of this study. b Number of articles per year. c Comparison of the cumulative number from a on a semi-logarithmic scale to the cumulative number of articles retrieved from using the single search term energy; the graphical presentations in a and b are inspired by and allow a direct comparison to [96]