Source Data Reference for:

City = Delft
Time = 1850

City	Year	Size	Size Comment	Year Comment	Author	Title	Location
Delft	1840	17,500			Jan Lahmeyer	http://www.populstat.info/	n/a
Delft	1850	18,000			Paul Bairoch	La population des villes europeennes de 800 a 1850