@article{10_4064_aa112_4_2,
     author = {Bjorn Poonen},
     title = {Sums of values of a rational function},
     journal = {Acta Arithmetica},
     pages = {333--343},
     year = {2004},
     volume = {112},
     number = {4},
     doi = {10.4064/aa112-4-2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa112-4-2/}
}