Sumsets of reciprocals in prime fields and multilinear Kloosterman sums

We obtain new results on additive properties of the set $$I^{-1}=\{x^{-1}:x\in I\}$$ where $I$ is an arbitrary interval in the field of residue classes modulo a large prime $p$. We combine our results with multilinear exponential sum estimates and obtain new results on incomplete multilinear Kloosterman sums.