1. Ougarov, V. (1979) Théorie de la Relativité Restreinte. MIR, Moscow.
2. Weyl, H. (1918, 1958) Space, Time, Matter. Springer, Berlin.
3. Pommaret, J.-F. (1988) Lie Pseudogroups and Mechanics. Gordon and Breach, New York.
4. The Mathematical Foundations of Elasticity and Electromagnetism Revisited