@article{JGG_2000_4_1_a2,
     author = {H. Pottmann and R. Krasauskas and B. Hamann and K. Joy and W. Seibold},
     title = {On {Piecewise} {Linear} {Approximation} of {Quadratic} {Functions}},
     journal = {Journal for geometry and graphics},
     pages = {031--054},
     publisher = {mathdoc},
     volume = {4},
     number = {1},
     year = {2000},
     url = {http://geodesic.mathdoc.fr/item/JGG_2000_4_1_a2/}
}