Leal, Wilmer Max Planck Institute for Mathematics in the Sciences, Max Planck Society;
Restrepo, Guillermo Max Planck Institute for Mathematics in the Sciences, Max Planck Society;
Leal, W., & Restrepo, G. (2019). Formal structure of periodic system of elements. Proceedings of the Royal Society of London / A, 475(2224): 20180581. doi:10.1098/rspa.2018.0581.