This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Measuring round town from afarSSJZ. Measuring round town from distance From edition of Shu Shu Jiu Zhang Qin Jiushao PDold Check categories November en MathematicalTreatiseinNineSections zh History of China Manuscripts Science and technology in China Mathematics books book covers single pages etc History of technology