1. Integrable equations of the dispersionless Hirota type and hypersurfaces in the Lagrangian grassmannian;Ferapontov;Int Math Res Not IMRN,2010
2. Evolutionary Hirota type (2+1)-dimensional equations: Lax pairs, recursion operators and bi-hamiltonian structures;Sheftel;SIGMA,2018
3. Applications of lie groups to differential equations, graduate texts in mathematics, Vol. 107;Olver,1986
4. Multi-Hamiltonian structure of Plebański’s second heavenly equation;Neyzi;J Phys A: Math Gen,2005
5. Recursion operators and tri-Hamiltonian structure of the first heavenly equation of Plebański;Sheftel;SIGMA,2016