- A V Mikhailov, V S Novikov, “Perturbative symmetry approach”, J. Phys. A: Math. Gen., 35, № 22, 2002,
4775 
- Antonio Moro, Reference Module in Materials Science and Materials Engineering, 2024
- Nitin Serwa, “Master symmetries of non-linear systems”, Phys. Scr., 99, № 6, 2024,
065037