Classification Theory of Riemannian Manifolds : Harmonic quasiharmonic and biharmonic functions Preface and historical note Laplace Beltrami operator Harmonic functions Quasiharmonic functions Bounded biharmonic functions Dirichlet finite biharmonic functions Bounded dirichlet finite biharmonic functions Harmonic quasiharmonic and biharmonic degeneracies Riesz representation of biharmonic functions Biharmonic Green’s function  Biharmonic Green’s function : Definition and existence Relation of O  N to other null classes Hadamard’s conjecture on the Green’s function of a clamped plate.