@article{10_4064_aa_24_1_1_9,
     author = {P. Erd\"os and I. Ruzsa and A. S\'ark\"ozi},
     title = {On the number of solutions of f(n) = a for additive functions},
     journal = {Acta Arithmetica},
     pages = {1--9},
     publisher = {mathdoc},
     volume = {24},
     number = {1},
     year = {1973},
     doi = {10.4064/aa-24-1-1-9},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa-24-1-1-9/}
}