On spin 3 interacting with gravity
  Recently Boulanger and Leclercq have constructed cubic four derivative $3-3-2$ vertex for interaction of spin 3 and spin 2 particles. This vertex is trivially invariant under the gauge transformations of spin 2 field, so it seemed that it could be expressed in terms of (linearized) Riemann tensor. And indeed in this paper we managed to reproduce this vertex in the form $R \partial \Phi \partial \Phi$, where $R$ -- linearized Riemann tensor and $\Phi$ -- completely symmetric third rank tensor. Then we consider deformation of this vertex to $(A)dS$ space and show that such deformation produce "standard" gravitational interaction for spin 3 particles (in linear approximation) in agreement with general construction of Fradkin and Vasiliev. Then we turn to the massive case and show that the same higher derivative terms allows one to extend gauge invariant description of massive spin 3 particle from constant curvature spaces to arbitrary gravitational backgrounds satisfying $R_{\mu\nu} = 0$. 
Yu. M. Zinoviev