@article{CMH_1968__43_139369,
     author = {R. Narasimhan and K. Chandrasekharan},
     title = {An {Approximate} {Reciprocity} {Formula} for {Some} {Exponential} {Sums.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {296--310},
     publisher = {mathdoc},
     volume = {43},
     year = {1968},
     zbl = {0157.09303},
     url = {http://geodesic.mathdoc.fr/item/CMH_1968__43_139369/}
}