Comments on Yang and Meng (2020) “The evolution and research framework of carbon footprint: Based on the perspective of knowledge mapping” [Ecol. Indic., 112, 106125]

Yang and Meng (2020) used sub-optimal search keywords and methods to publish a bibliometric paper in Ecological Indicators. There are two questionable parts to the original paper: a filter could be used to retrieve a more accurate set of data and the use of sub-optimal search keywords. There is a big difference between the two results that were searched using search keywords ("carbon footprint", "carbon footprints", and "carbon footprinting") which we suggested and ("carbon footprint") which authors used. Finally, an appropriate method and search keywords were presented.