1. Ibragimov, NH. A practical course in differential equations and mathematical modelling: classical and new methods, Nonlinear mathematical models, symmetry and invariance principles, 3rd ed. 2006.
2. Group analysis of differential equations;Ovsiannikov,1982
3. Ibragimov, NH. CRC handbook of Lie Groups, Analysis of differential equations; 1995.
4. Applications of Lie groups to differential equations;Olver,1993
5. Differential equations: their solution using symmetries;Stephani,1989