@article{ARM_1986__22_4_a1,
     author = {Narang, T. D.},
     title = {Approximation relative to an ultra function},
     journal = {Archivum mathematicum},
     pages = {181--186},
     publisher = {mathdoc},
     volume = {22},
     number = {4},
     year = {1986},
     mrnumber = {868532},
     zbl = {0608.41016},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ARM_1986__22_4_a1/}
}