1. Classical hard sphere 3-body problem;Thurston;Bull. Amer. Phys. Soc.,1964
2. Uniform Estimates on the Number of Collisions in Semi-Dispersing Billiards
3. Systems of locally interacting and repelling particles that are moving in space;Galperin;Tr. Mosk. Mat. Obs.,1981
4. Maximum number of collisions among identical hard spheres
5. [8] Serre, D. . Estimating the number and the strength of collisions in molecular dynamics. Preprint, 2019, arxiv:1903.05866 v1.