Cancellations between Kloosterman sums modulo a prime power with prime   arguments
  We obtain a nontrivial bound for cancellations between the Kloosterman sums modulo a large prime power with a prime argument running over very short interval, which in turn is based on a new estimate on bilinear sums of Kloosterman sums. These results are analogues of those obtained by various authors for Kloosterman sums modulo a prime. However the underlying technique is different and allows us to obtain nontrivial results starting from much shorter ranges. 
Kui Liu, Igor E. Shparlinski and Tianping Zhang
math.NT