1. Allen, M., Kriventsov, D., Neumayer, R.: Sharp quantitative Faber-Krahn inequalities and the Alt–Caffarelli–Friedman monotonicity formula. Ars Inven. Anal. pages Paper No. 1,49, (2023)
2. Alt, H.W., Caffarelli, L.A., Friedman, A.: Variational problems with two phases and their free boundaries. Trans. Am. Math. Soc. 282(2), 431–461 (1984)
3. Beals, R., Gaveau, B., Greiner, P.: The Green function of model step two hypoelliptic operators and the analysis of certain tangential Cauchy Riemann complexes. Adv. Math. 121(2), 288–345 (1996)
4. Bonfiglioli, A., Lanconelli, E., Uguzzoni, F.: Stratified Lie groups and potential theory for their sub-Laplacians. Springer Science & Business Media, Berlin (2007)
5. Caffarelli, L.: A monotonicity formula for heat functions in disjoint domains. Boundary Value Problems for PDE’s and Applications, dedicated to E. Magenes (JL Lions, C. Baiocchi, eds.), Masson, Paris, pp. 53–60, (1993)