1. Symmetry groups and group invariant solutions of partial differential equations;Olver;J. Differential Geom.,1979
2. Hydrodynamics;Birkhoff,1960
3. Group Analysis of Differential Equations;Ovsiannikov,1982
4. Similarity Methods for Differential Equations;Bluman,1974
5. Symmetries and Differential Equations;Bluman,1989