@article{ZNSL_1973_33_a8,
     author = {E. V. Podsypanin},
     title = {On the sums of squares of squares-free numbers},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {116--131},
     publisher = {mathdoc},
     volume = {33},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1973_33_a8/}
}