Ho Peng Yoke (1997). "Gunpowder". In Selin, Helaine (ed.). Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures. Springer. p. 389. ISBN978-0-7923-4066-9. Archived from the original on 9 October 2013. Retrieved 30 July 2013.
Ho Peng Yoke (1997). "Gunpowder". In Selin, Helaine (ed.). Encyclopaedia of the History of Science, Technology, and Medicine in Non-Western Cultures. Springer. p. 389. ISBN978-0-7923-4066-9. Archived from the original on 9 October 2013. Retrieved 30 July 2013.