Biharmonic Immersion in Cartan Hadamard manifold

If $(N^{m+p},h)$ is a Cartan-Hadamard manifold such that $Ric(h)\geq -G(r_{N}(x))$where$G(0)\geq 1, G^{'}\geq 0$and$G^{-1/2}\not\in L^{1}(+\infty)$theneveryproperbiharmonicisometricimmersion$\phi : M^{m}\rightarrow(N^{m+p},h)$ is a harmonic map.