Fig. 4

Mapping of terms in the research on nicotine replacement therapy (NRT). a shows the co-occurrence network of terms that extracted from the title or abstract of at least 10 articles. Colors represent groups of terms that are relatively strongly linked to each other. The size of a term signifies the number of publications related to NRT in which the term was appeared, and the distance between two terms represents an estimated indication of the relatedness of these terms. b represents the earlier (blue color) or later (red color) years when the term appeared