1. Group Analysis of Differential Equations;Ovsiannikov,1982
2. CRC Handbook of Lie Group Analysis of Differential Equations;Ibragimov,1994
3. Differential Equations: Their Solution Using Symmetries;Stephani,1989
4. Applications of Lie Groups to Differential Equations;Olver,1993
5. Symmetry Methods for Differential Equations;Hydon,2000