Hacker, Barton C (1968), "Greek Catapults and Catapult Technology: Science, Technology, and War in Ancient World", Technology and Culture, 9 (1): 34–50, doi:10.2307/3102042, JSTOR3102042, S2CID112617914.
Hacker, Barton C (1968), "Greek Catapults and Catapult Technology: Science, Technology, and War in Ancient World", Technology and Culture, 9 (1): 34–50, doi:10.2307/3102042, JSTOR3102042, S2CID112617914.
Chevedden et al. (1995), abstract at medievalists.net, quote: "The trebuchet, invented in China between the fifth and third centuries B.C.E., reached the Mediterranean by the sixth century C.E."
middle-ages.org.uk
"Catapults", middle-ages.org.uk, archived from the original on 2010-09-24. (subscription required)
Hacker, Barton C (1968), "Greek Catapults and Catapult Technology: Science, Technology, and War in Ancient World", Technology and Culture, 9 (1): 34–50, doi:10.2307/3102042, JSTOR3102042, S2CID112617914.