UNO, Deparment of Economic and Social Affairs, Guidelines on the use of electronic data collection technologies in population and housing censuses, 2019-01, p, 22 ([Internet, 2020-01-30](https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=2ahUKEwjU8oyylq7nAhWQsaQKHQ2mAvgQFjAAegQIAxAB&url=https%3A%2F%2Funstats.un.org%2Funsd%2Fdemographic%2Fstandmeth%2Fhandbooks%2Fdata-collection-census-201901.pdf&usg=AOvVaw1uAWe6j4xoGo1Nq0uSMcpo))