@article{AM2_1985__29_137093,
     author = {Arthur G. Werschulz},
     title = {Counterexamples in optimal quadrature.},
     journal = {Aequationes mathematicae},
     pages = {183--203},
     year = {1985},
     volume = {29},
     zbl = {0615.65016},
     url = {http://geodesic.mathdoc.fr/item/AM2_1985__29_137093/}
}