(A) Complete keyword co-occurrence network developed to visualise the importance of the research areas. Vertex colours are based on research areas or clusters and vertex size is proportional to the frequency of keyword occurrence. (B) Simplified network based on cluster centres and most frequent keywords (> Q95 or number of occurrences ≥ 4). Overall vertex sizes are proportional to the log-transformed number of occurrences and inner circles to the proportion within each research area. Label sizes have been rescaled to avoid overlapping.