1. P. Olver, Applications of Lie Groups to Differential Equations (Springer-Verlag, New York, 1986).
2. G. Bluman and S.C. Anco, Symmetry and Integration Methods for Differential Equations, Springer Applied Mathematics Series 154 (Springer-Verlag, New York, 2002).
3. G. Bluman, A. Cheviakov, S.C. Anco, Applications of Symmetry Methods to Partial Differential Equations, Springer Applied Mathematics Series 168, (Springer, New York, 2010).
4. L. Martinez Alonso, Lett. Math. Phys. 3, 419–424 (1979).
5. Y. Kosmann-Schwarzbach, The Noether theorems. Invariance and conservation laws in the twentieth century, Sources and Studies in the History of Mathematics and Physical Sciences (translated, revised, and augmented by B.E. Schwarzbach), (Springer, New York, 2011).