@misc{pordata2020porto,
  title = {Porto Population evolution by gender (1981-2019)}
  author = {PORDATA},
  url = {https://www.pordata.pt/Municipios/Popula%c3%a7%c3%a3o+residente++estimativas+a+31+de+Dezembro+total+e+por+sexo-136},
  year = {2020}
}