@article{NUMA_1975__25_132365,
     author = {R. Hettich},
     title = {Kriterien erster und zweiter {Ordnung} f\"ur lokal beste {Approximationen} bei {Problemen} mit {Nebenbedingungen.}  - {On} {First} and {Second} {Order} {Conditions} for {Locally} {Best} {Approximations} for {Constraint} {Problems.}},
     journal = {Numerische Mathematik},
     pages = {109--122},
     publisher = {mathdoc},
     volume = {25},
     year = {1975},
     zbl = {0303.41021},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1975__25_132365/}
}