@article{10_21136_CMJ_2023_0394_22,
     author = {Chen, Gongrui and Wang, Wenxiao},
     title = {On the $r$-free values of the polynomial $x^2 + y^2 + z^2 +k$},
     journal = {Czechoslovak Mathematical Journal},
     pages = {955--969},
     publisher = {mathdoc},
     volume = {73},
     number = {3},
     year = {2023},
     doi = {10.21136/CMJ.2023.0394-22},
     mrnumber = {4632868},
     zbl = {07729548},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.2023.0394-22/}
}