Conrad Haas (1509–1576) was a military engineer of the Holy Roman Empire, who is often cited as the first person to describe a multistage rocket in writing, although some historians attribute that distinction to Jiao Yu in 14th Century China. Between 1529 and 1556, he wrote a book in German language in which he described rocket technology, involving the combination of fireworks and weapons technologies. This manuscript was discovered in 1961, in the Sibiu public records (Sibiu public records Varia II 374).