Classical Relativistic Many-Body DynamicsTrump, M.A., Schieve, W.C
Springer, Fundamental Theories of Physics, Vol. 103
This relativistic covariant many-body formulation overcomes the no go theorem by Jordan and Sudarshan  by giving up the locality of the interactions and the individual mass-shell conditions. These are not simply cosmetic upgrades but have serious consequences on how we should understand classical physics.
"The single particle has no significance; it is the whole system that counts" --Lanczos
 FROM CLASSICAL TO
Giampiero Esposito, Giuseppe Marmo