@article{JIS_2015__18_9_a0,
     author = {Girstmair, Kurt},
     title = {Periodic continued fractions and {Kronecker} symbols},
     journal = {Journal of integer sequences},
     publisher = {mathdoc},
     volume = {18},
     number = {9},
     year = {2015},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2015__18_9_a0/}
}