Source Data Reference for:

City = Kazan
Time = 1800

City	Year	Size	Size Comment	Year Comment	Author	Title	Location
Kazan	1800	17,000			Jan Lahmeyer	http://www.populstat.info/	n/a
Kazan	1800	50,000			Paul Bairoch	La population des villes europeennes de 800 a 1850
Kazan	1800	25,000			Tertius Chandler	Four thousand years of urban growth	p488
Kazan	1800	25,000			Tertius Chandler	Four thousand years of urban growth	p25