@article{NUMA_1987__52_5_133222,
     author = {Gerhard Opfer and Hans Joachim Oberle},
     title = {The {Derivation} of {Cubic} {Splines} with {Obstacles} by {Methods} of {Optimization} and {Optimal} {Control.}},
     journal = {Numerische Mathematik},
     pages = {17--32},
     publisher = {mathdoc},
     volume = {52},
     number = {5},
     year = {1987},
     zbl = {0628.41012},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1987__52_5_133222/}
}