@article { LPGV10,
author = {   Langevin, Philippe and  Gillot, Val\'erie   },
title  = {   Estimation of  Some Exponential Sums by means of weighted degree   },
journal = {  Glasgow Math. Journal },
number = { 02 },
pages = {  315--324 },
volume  = { 52 },
year = {2010},
rang = {A},
}