 Differential invariants and group foliation for the complex MongeAmpère
equation, J. Phys. A: Gen. Vol. 34, 137156 (2001).
 Superintegrable systems
in quantum mechanics and classical Lie theory, J. Math. Phys. Vol. 42, 659673
(2001) (with P. Tempesta and P. Winternitz).
 Group foliation and
noninvariant solutions of the heavenly equation, J. Phys. A: Math. Gen. Vol.
34, 92439263 (2001) (with L. Martina and P. Wintermitz).
 Partner symmetries
of the complex MongeAmpère
equation yield hyperKöhler metrics without continuous symmetries, J. Phys. A:
Math. Gen., Vol. 36, 1002310037 (2003) (with A.A. Malykh and Y. Nutku).

Symmetry group analysis and invariant solutions of hydrodynamictype systems,
Intern. J. Math. Sciences, Vol. 2004, 487534 (2004).
 Partner symmetries and
noninvariant solutions of fourdimensional heavenly equations,
arxiv:mathph/0403020 (2004) (with A. A. Malykh and Y. Nutku).
