A new paper “Three Decades of Research on Smart Cities‘ by Ayyoob Sharifi, Zaheer Allam, Bakhtiar Feizizadeh, and Hessam Ghamari, published in Sustainability 2021, 13, 7140, gives an overview of the structure and trends in the literature on smart cities. It is a bibliometric analysis and science mapping using VOSviewer and CiteSpace to identify the thematic focus of over 5000 articles indexed in the Web of Science.