@article{AM2_1978__17_136742,
     author = {L.L. Keener and W.H. Ling},
     title = {Approximation under an arc length constraint.},
     journal = {Aequationes mathematicae},
     pages = {235--240},
     publisher = {mathdoc},
     volume = {17},
     year = {1978},
     zbl = {0379.41017},
     url = {http://geodesic.mathdoc.fr/item/AM2_1978__17_136742/}
}