@article{MABA_1989_3_2_a10,
     author = {Rumen K. Uluchev},
     title = {B-Splines with {Birkhoff} {Knots.} {Applications} in the {Approximations} and {Shape-Preserving} {Interpolation}},
     journal = {Mathematica balkanica},
     pages = {225},
     publisher = {mathdoc},
     volume = {3},
     number = {2},
     year = {1989},
     url = {http://geodesic.mathdoc.fr/item/MABA_1989_3_2_a10/}
}