@article{ZNSL_2006_337_a4,
     author = {N. Yu. Dodonov and V. V. Zhuk},
     title = {On approximating periodic functions by singular integrals with positive kernels},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {51--72},
     year = {2006},
     volume = {337},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2006_337_a4/}
}