Second-order differential invariants of the rotation group O(*n*) and of its extensions: *E*(*n*), *P*(1, *n*), *G*(1, *n*)WI Fushchich, IA Yegorchenko Acta Applicandae Mathematica 28, 69-92, 1992 | 52 | 1992 |

On reduction of the nonlinear many-dimensional wave equations and compatibility of the d’Alembert–Hamilton system WI Fushchych, RZ Zhdanov, IA Yegorchenko J. Math. Anal. Appl 160, 352-360, 1991 | 29* | 1991 |

Nonlinear representation of the Poincaré algebra and invariant equations IA Yehorchenko Symmetry Analysis of Equations of Mathematical Physics, 62-66, 1992 | 23 | 1992 |

The symmetry and exact solutions of the nonlinear d’Alembert equation for complex fields WI Fushchych, IA Yegorchenko J. Phys. A 22, 2643-2652, 1989 | 20 | 1989 |

Differential invariants for Galilei algebra WI Fushchych, IA Yehorchenko Dokl. Acad. Nauk. Ukr. SSR, Ser. A, 19-34, 1989 | 17* | 1989 |

Group classification of multidimensional nonlinear wave equations OF Vasilenko, IA Yehorchenko Proceedings of Institute of Mathematics of NAS of Ukraine 36, 63-66, 2001 | 15 | 2001 |

Differential invariants for a nonlinear representation of the Poincaré algebra. Invariant equations I Yehorchenko Proc. of the Second Int. Conf.“Symmetry in Nonlinear Mathematical Physics …, 1997 | 14 | 1997 |

Differential invariants for Poincaré algebra and conformal algebra WI Fushchych, IA Yehorchenko Dokl. Acad. Nauk. Ukr. SSR, Ser. A, 46-53, 1989 | 14* | 1989 |

Group classification of generalized eikonal equations RO Popovych, IA Ehorchenko Ukrainian Mathematical Journal 53 (11), 1841-1850, 2001 | 12 | 2001 |

Group classification with respect to hidden symmetry I Yehorchenko Proc. Inst. Math. NAS Ukraine 50, 290-297, 2004 | 11 | 2004 |

Differential invariants and construction of conditionally invariant equations I Yehorchenko arXiv preprint math-ph/0304029, 2003 | 10 | 2003 |

Conditional invariance and exact solutions of the Klein-Gordon-Fock equation IA Yehorchenko, AI Vorobyova Reports of the Nat. Acad. Sci. of Ukraine, 19-22, 1992 | 9 | 1992 |

Sets of conditional symmetry operators and exact solutions for wave and generalised heat equations IA Yehorchenko, AI Vorobyova Proceedings of Fifth International Conference” Symmetry in Nonlinear …, 2004 | 8 | 2004 |

Second-order differential invariants for some extensions of the Poincaré group and invariant equations I Yehorchenko Journal of Nonlinear Mathematical Physics 3 (1-2), 186-195, 1996 | 5 | 1996 |

Non-Lie ansatzen and conditional symmetry of the nonlinear Schrödinger equation VI Fushchich, IA Egorchenko Ukrainian Mathematical Journal 43 (12), 1507-1515, 1991 | 5* | 1991 |

On symmetry properties of complex-valued nonlinear wave equations VI Fushchich, IA Egorchenko Doklady Akademii Nauk SSSR 298 (2), 347-351, 1988 | 5* | 1988 |

Conditional symmetry and reductions for the two-dimensional nonlinear wave equation. I. General case I Yehorchenko arXiv preprint arXiv:1010.4913, 2010 | 4 | 2010 |

Solutions of the system of d'Alembert and eikonal equations, and classification of reductions of PDEs I Yehorchenko Journal of Physics: Conference Series 621 (1), 012018, 2015 | 3 | 2015 |

Ansatzes and exact solutions for nonlinear Schrodinger equations I Yehorchenko arXiv preprint arXiv:1412.1889, 2014 | 3 | 2014 |

On reduction of multi-dimensional non-linear wave equation to two-dimensional equations WI Fushchych, IA Yehorchenko arXiv preprint math-ph/0610020, 2006 | 3 | 2006 |