Source: https://www.researchgate.net/profile/Albrecht-Heeffer/publication/266334553_Recreations_Mathematiques_1624_A_Study_on_its_Authorship_Sources_and_Influence/links/547321d40cf216f8cfae9d84/Recreations-Mathematiques-1624-A-Study-on-its-Authorship-Sources-and-Influence.pdf