@article{JEMS_2006_8_3_a1,
     author = {Mei-Chu Chang},
     title = {On sum-product representations in $\Bbb Z_q$},
     journal = {Journal of the European Mathematical Society},
     pages = {435--463},
     publisher = {mathdoc},
     volume = {8},
     number = {3},
     year = {2006},
     doi = {10.4171/jems/62},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/jems/62/}
}