He became not only on of the founders of the " Ricci calculus" but also an efficient organiser (he was a founder of the Mathematical Center at Amsterdam in 1946) and an astute investor.
Siya ay naging hindi lamang sa mga founder ng "Ricci calculus" kundi pati na rin ng isang mahusay na Organizer (siya ay isang tagapagtatag ng matematika Center sa Amsterdam noong 1946) at isang astute mamumuhunan.