A factorization result for generalized Nevanlinna functions of the classN k A Dijksma, H Langer, A Luger, Y Shondin Integral Equations and Operator Theory 36 (1), 121-125, 2000 | 75 | 2000 |

Sum rules and constraints on passive systems A Bernland, A Luger, M Gustafsson Journal of Physics A: Mathematical and Theoretical 44 (14), 145205, 2011 | 71 | 2011 |

An operator theoretic interpretation of the generalized Titchmarsh-Weyl coefficient for a singular Sturm-Liouville problem P Kurasov, A Luger Mathematical Physics, Analysis and Geometry 14 (2), 115-151, 2011 | 39 | 2011 |

On the number of negative eigenvalues of the Laplacian on a metric graph J Behrndt, A Luger Journal of Physics A: Mathematical and Theoretical 43 (47), 474006, 2010 | 32 | 2010 |

A factorization of regular generalized Nevanlinna functions A Luger Integral Equations and Operator Theory 43 (3), 326-345, 2002 | 31 | 2002 |

Minimal realizations of scalar generalized Nevanlinna functions related to their basic factorization A Dijksma, H Langer, A Luger, Y Shondin Spectral Methods for Operators of Mathematical Physics, 69-90, 2004 | 22 | 2004 |

Mark Krein's method of directing functionals and singular potentials C Fulton, H Langer, A Luger Mathematische Nachrichten 285 (14‐15), 1791-1798, 2012 | 21 | 2012 |

A characterization of generalized poles of generalized Nevanlinna functions A Luger Mathematische Nachrichten 279 (8), 891-910, 2006 | 18 | 2006 |

Generalized zeros and poles of\mathcal N_\kappa-functions: on the underlying spectral structure S Hassi, A Luger Methods of Functional Analysis and Topology 12 (02), 131-150, 2006 | 15 | 2006 |

A class of 2* 2-matrix functions H Langer, A Luger Glasnik matematički 35 (1), 149-160, 2000 | 15 | 2000 |

Generalized zeros and poles of -functions: On the underlying spectral structure S Hassi, A Luger | 15* | |

An analytic characterization of the eigenvalues of self-adjoint extensions J Behrndt, A Luger Journal of Functional Analysis 242 (2), 607-640, 2007 | 14 | 2007 |

Convergence of generalized Nevanlinna functions H Langer, A Luger, V Matsaev Acta Sci. Math.(Szeged) 77 (3-4), 425-437, 2011 | 11 | 2011 |

Approximation of *N* _{κ} ^{∞} -functions I: Models and RegularizationA Dijksma, A Luger, Y Shondin Spectral theory in inner product spaces and applications, 87-112, 2008 | 11 | 2008 |

Passive approximation and optimization using B-splines Y Ivanenko, M Gustafsson, BLG Jonsson, A Luger, B Nilsson, S Nordebo, ... SIAM Journal on Applied Mathematics 79 (1), 436-458, 2019 | 10 | 2019 |

A characterization of Herglotz–Nevanlinna functions in two variables via integral representations A Luger, M Nedic Arkiv för Matematik 55 (1), 199-216, 2017 | 10 | 2017 |

Minimal Models for -functions A Dijksma, A Luger, Y Shondin Operator theory and indefinite inner product spaces, 97-134, 2005 | 10 | 2005 |

Minimal Models for -functions A Dijksma, A Luger, Y Shondin Operator theory and indefinite inner product spaces, 97-134, 2005 | 10 | 2005 |

Minimal Models for -functions A Dijksma, A Luger, Y Shondin Operator theory and indefinite inner product spaces, 97-134, 2005 | 10 | 2005 |

On the negative squares of a class of self‐adjoint extensions in Krein spaces J Behrndt, A Luger, C Trunk Mathematische Nachrichten 286 (2‐3), 118-148, 2013 | 9 | 2013 |