@article {127, title = {Convergence of Nonlinear Observers on $\mathbb{R}^n$ with a Riemannian Metric {(Part II)}}, journal = {IEEE Transactions on Automatic Control}, volume = {61}, number = {10}, year = {2016}, month = {October}, pages = {2848-2860}, author = {R. G. Sanfelice and L. Praly} }