1. Symmetries and Differential Equations;Bluman,1989
2. CRC Handbook of Lie Group Analysis of Differential Equations;Ibragimov,1993
3. Applications of Lie Groups to Differential Equations;Olver,1993
4. Group Analysis of Differential Equations;Ovsiannikov,1982
5. Studies on the invariances and symmetries of certain nonlinear evolution equations;Kaliappan,1981