Sharp Weyl-Type Formulas of the Spectral Functions for Biharmonic   Steklov Eigenvalues
  In this paper, by explicitly calculating the principal symbols of pseudodifferential operators and by applying H\"omander's spectral function theorem, we obtain the Weyl-type asymptotic formulas with sharp remainder estimates for the counting functions of the two classes of biharmonic Steklov eigenvalues $\lambda_k$ and $\mu_k$ in a smooth bounded domain of a Riemannian manifold. This solves a longstanding challenging problem. 
Genqian Liu
math.AP