Weyl function and spectral properties of self-adjoint extensions JF Brasche, M Malamud, H Neidhardt Integral Equations and Operator Theory 43, 264-289, 2002 | 124 | 2002 |

Geometry of quantum principal bundles I M Durdević Communications in Mathematical Physics 175, 457-520, 1996 | 120* | 1996 |

Potential approximations to δ': an inverse Klauder phenomenon with norm-resolvent convergence P Exner, H Neidhardt, VA Zagrebnov Communications in Mathematical Physics 224, 593-612, 2001 | 119 | 2001 |

On the spectrum of the lattice spin-boson Hamiltonian for any coupling: 1D case M Muminov, H Neidhardt, T Rasulov Journal of Mathematical Physics 56 (5), 2015 | 98 | 2015 |

Scattering matrices and Weyl functions J Behrndt, MM Malamud, H Neidhardt Proceedings of the London Mathematical Society 97 (3), 568-598, 2008 | 97 | 2008 |

Sturm–Liouville boundary value problems with operator potentials and unitary equivalence M Malamud, H Neidhardt Journal of Differential Equations 252 (11), 5875-5922, 2012 | 70 | 2012 |

On error estimates for the Trotter–Kato product formula H Neidhardt, VA Zagrebnov Letters in Mathematical Physics 44, 169-186, 1998 | 63 | 1998 |

On abstract linear evolution equations, I H Neidhardt Mathematische Nachrichten 103 (1), 283-298, 1981 | 63 | 1981 |

Trotter–Kato product formula and operator-norm convergence H Neidhardt, VA Zagrebnov Communications in Mathematical Physics 205, 129-159, 1999 | 60 | 1999 |

On the unitary equivalence of absolutely continuous parts of self-adjoint extensions MM Malamud, H Neidhardt Journal of Functional Analysis 260 (3), 613-638, 2011 | 58 | 2011 |

Spectral theory of infinite quantum graphs P Exner, A Kostenko, M Malamud, H Neidhardt Annales Henri Poincaré 19, 3457-3510, 2018 | 53 | 2018 |

Linear non-autonomous Cauchy problems and evolution semigroups H Neidhardt, VA Zagrebnov | 49 | 2009 |

Inverse spectral theory for symmetric operators with several gaps: scalar-type Weyl functions S Albeverio, JF Brasche, MM Malamud, H Neidhardt Journal of Functional Analysis 228 (1), 144-188, 2005 | 49 | 2005 |

Evanescent channels and scattering in cylindrical nanowire heterostructures PN Racec, ER Racec, H Neidhardt Physical Review B 79 (15), 155305, 2009 | 42 | 2009 |

Spectral Shift Function and Hilbert‐Schmidt Perturbation: Extensions of Some Work of LS Koplienko H Neidhardt Mathematische Nachrichten 138 (1), 7-25, 1988 | 42 | 1988 |

Scattering matrices and Dirichlet-to-Neumann maps J Behrndt, MM Malamud, H Neidhardt Journal of Functional Analysis 273 (6), 1970-2025, 2017 | 37 | 2017 |

The Trotter-Kato product formula for Gibbs semigroups H Neidhardt, VA Zagrebnov Communications in mathematical physics 131, 333-346, 1990 | 34 | 1990 |

Trace formulas for additive and non-additive perturbations M Malamud, H Neidhardt Advances in Mathematics 274, 736-832, 2015 | 33 | 2015 |

On the point spectrum of self-adjoint extensions J Brasche, H Neidhardt, J Weidmann Mathematische Zeitschrift 214, 343-355, 1993 | 33 | 1993 |

Fractional powers of self-adjoint operators and Trotter-Kato product formula H Neidhardt, VA Zagrebnov Integral Equations and Operator Theory 35, 209-231, 1999 | 32 | 1999 |