Exotic charmonium-like spectroscopy at LHCb: a study of the X(3872) and of the Z(4430)^-

I will report on the recent LHCb results on the evidence for the decay $X(3872)\to \psi (2S)\gamma$, and on the improved measurement of the mass and width of the $Z(4430{)}^{-}$, the determination of its quantum numbers and the observation of its resonant character.