@article{NUMA_1975__25_132377,
     author = {K. Jetter},
     title = {Optimale {Quadraturformeln} mit semidefiniten {Peano-Kernen.}  - {Optimal} {Integration} {Formulas} with {Semidefinite} {Peano-Kernels.}},
     journal = {Numerische Mathematik},
     pages = {239--250},
     publisher = {mathdoc},
     volume = {25},
     year = {1975},
     zbl = {0304.65019},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1975__25_132377/}
}