Seventh International Congress of Hygiene and Demography, London: participants standing on a monumental staircase with a… https://www.rawpixel.com/image/13970983/image-person-pattern-musicFree Image from public domain licensePopulation of all the principal places throughout the World : from the last census, printed by order of Parliament ...… https://www.rawpixel.com/image/13992284/image-background-paper-bookFree Image from public domain license