Bronze Arme Défense - Sécurité nationale Héběi fāxiàn Yuán Míng shíqí guǎnzhuàng huǒqì——Tóng pào, tóng chòng de yánjiū (shàng) 河北发现元明时期管状火器——铜炮、铜铳的研究(上) = The Yuan-Ming Period Tubular Firearms Discovered in Hebei: A Study of the Bronze Canons and Guns (Part One)