On the Hyers–Ulam stability of the linear differential equation D Popa, I Raşa Journal of Mathematical Analysis and Applications 381 (2), 530-537, 2011 | 162 | 2011 |

Ulam stability of operators J Brzdek, D Popa, I Rasa, B Xu Academic Press, 2018 | 153 | 2018 |

On the stability of the linear functional equation in a single variable on complete metric groups SM Jung, D Popa, MT Rassias Journal of Global Optimization 59, 165-171, 2014 | 143 | 2014 |

Hyers–Ulam–Rassias stability of a linear recurrence D Popa Journal of mathematical analysis and applications 309 (2), 591-597, 2005 | 119 | 2005 |

Hyers-Ulam stability of the linear recurrence with constant coefficients D Popa Advances in Difference Equations 2005 (2), 1-7, 2005 | 108 | 2005 |

On the Hyers-Ulam stability of a first order partial differential equation N Lungu, D Popa Carpathian Journal of Mathematics, 77-82, 2012 | 98 | 2012 |

Hyers–Ulam stability of the linear differential operator with nonconstant coefficients D Popa, I Raşa Applied Mathematics and Computation 219 (4), 1562-1568, 2012 | 88 | 2012 |

Functional equations in mathematical analysis TM Rassias, J Brzdek Springer, 2011 | 74 | 2011 |

The Hyers-Ulam stability of nonlinear recurrences J Brzd k, D Popa, B Xu Journal of mathematical analysis and applications 335 (1), 443-449, 2007 | 73 | 2007 |

On the stability of the linear differential equation of higher order with constant coefficients DS Cîmpean, D Popa Applied Mathematics and Computation 217 (8), 4141-4146, 2010 | 65 | 2010 |

Hyers–Ulam stability of Euler’s equation DS Cimpean, D Popa Applied Mathematics Letters 24 (9), 1539-1543, 2011 | 60 | 2011 |

Asymptotic aspect of the quadratic functional equation in multi-normed spaces MS Moslehian, K Nikodem, D Popa Journal of Mathematical Analysis and Applications 355 (2), 717-724, 2009 | 58 | 2009 |

Remarks on stability of linear recurrence of higher order J Brzdȩk, D Popa, B Xu Applied Mathematics Letters 23 (12), 1459-1463, 2010 | 57 | 2010 |

Hyers-Ulam stability for linear equations of higher orders J Brzdęk, D Popa, B Xu Acta Mathematica Hungarica 120 (1-2), 1-8, 2008 | 47 | 2008 |

Note on nonstability of the linear recurrence J Brzdk, D Popa, B Xu Abhandlungen aus dem Mathematischen Seminar der Universität Hamburg 76 (1 …, 2006 | 46 | 2006 |

On single-valuedness of set-valued maps satisfying linear inclusions K Nikodem, D Popa Banach J. Math. Anal 3 (1), 44-51, 2009 | 39 | 2009 |

On nonstability of the linear recurrence of order one J Brzdȩk, D Popa, B Xu Journal of Mathematical Analysis and Applications 367 (1), 146-153, 2010 | 38 | 2010 |

The Fréchet functional equation with application to the stability of certain operators D Popa, I Raşa Journal of Approximation Theory, 2011 | 37 | 2011 |

Additive selections of (alpha, beta)-subadditive set valued maps D Popa Glasnik matematički 36 (1), 11-16, 2001 | 35 | 2001 |

Selections of set-valued maps satisfying a linear inclusion in a single variable J Brzdȩk, D Popa, B Xu Nonlinear Analysis: Theory, Methods & Applications 74 (1), 324-330, 2011 | 32 | 2011 |