@article{NUMA_1987__52_5_133254,
     author = {Tommy Elfving and Lars-Erik Andersson},
     title = {An {Algorithm} for {Computing} {Constrained} {Smoothing} {Spline} {Functions.}},
     journal = {Numerische Mathematik},
     pages = {583--596},
     publisher = {mathdoc},
     volume = {52},
     number = {5},
     year = {1987},
     zbl = {0622.41006},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1987__52_5_133254/}
}