He formed his own group of young geometers and together they wrote teaching texts, as well as the 4 volumes of a differential geometry text, later translated in German and French.
Binuo niya ang kanyang sariling mga grupo ng mga kabataan geometers at magkasama nilang wrote pagtuturo text, pati na rin ang volume 4 ng isang kaugalian geometry text, mamaya isinalin sa Aleman at Pranses.