European Commission (Eurostat and Directorate-General for Regional and Urban Policy), International Labour Organization (ILO), Food and Agriculture Organization of the United Nations (FAO), Organisation for Economic Co-operation and Development (OECD), UN-Habitat, World Bank, "A recommendation on the method to delineate cities, urban and rural areas for international statistical comparisons", March 2020 (https://ec.europa.eu/eurostat/cros/system/files/bg-item3j-recommendation-e.pdf)