@article{MEM_2021_50_a17,
     author = {Todorova, Tatyana L.},
     title = {Lagrange's four square theorem with almost-prime numbers having a special form},
     journal = {Mathematics and Education in Mathematics},
     pages = {163--175},
     publisher = {mathdoc},
     volume = {50},
     year = {2021},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MEM_2021_50_a17/}
}