@article{10_4064_aa115_3_7,
     author = {Jan-Christoph Schlage-Puchta},
     title = {The exponential sum over squarefree integers},
     journal = {Acta Arithmetica},
     pages = {265--268},
     publisher = {mathdoc},
     volume = {115},
     number = {3},
     year = {2004},
     doi = {10.4064/aa115-3-7},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa115-3-7/}
}