@article{AM2_1990__39_2-3_137334,
     author = {Peter K\"ohler},
     title = {On the error of compound quadrature formulas for r-convex functions.},
     journal = {Aequationes mathematicae},
     pages = {6--18},
     publisher = {mathdoc},
     volume = {39},
     number = {2-3},
     year = {1990},
     zbl = {0698.41028},
     url = {http://geodesic.mathdoc.fr/item/AM2_1990__39_2-3_137334/}
}