@article{CMH_1979__54_139801,
     author = {R. Narasimhan and K. Chandrasekharan},
     title = {Exponential sums associated with algebraic number fields.},
     journal = {Commentarii mathematici Helvetici},
     pages = {523--561},
     publisher = {mathdoc},
     volume = {54},
     year = {1979},
     zbl = {0443.10027},
     url = {http://geodesic.mathdoc.fr/item/CMH_1979__54_139801/}
}