@article{10_4064_ba56_1_1,
     author = {Igor E. Shparlinski},
     title = {On the {Euler} {Function}  on {Differences} {Between} {the
Coordinates} of  {Points} on {Modular} {Hyperbolas}},
     journal = {Bulletin of the Polish Academy of Sciences. Mathematics},
     pages = {1--7},
     publisher = {mathdoc},
     volume = {56},
     number = {1},
     year = {2008},
     doi = {10.4064/ba56-1-1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ba56-1-1/}
}