@article{PSMIR_1977___S4_A14_0,
     author = {Widlund, Olof},
     title = {Best {Error} {Bounds} for {Approximation} by {Piecewise} {Polynomial} {Functions}},
     journal = {Publications des s\'eminaires de math\'ematiques et informatique de Rennes},
     eid = {14},
     pages = {1--13},
     publisher = {D\'epartement de Math\'ematiques et Informatique, Universit\'e de Rennes},
     number = {S4},
     year = {1977},
     language = {en},
     url = {http://www.numdam.org/item/PSMIR_1977___S4_A14_0/}
}