L. Blank, State Estimation Analysed as Inverse Problem, Lect. Notes Control Inform. Sci, vol.358, pp.335-346, 2005.
DOI : 10.1007/978-3-540-72699-9_27

URL : http://citeseerx.ist.psu.edu/viewdoc/summary?doi=

S. Diop, V. Fromion, and J. W. Grizzle, A global exponential observer based on numerical differentiation, Proceedings of the 40th IEEE Conference on Decision and Control (Cat. No.01CH37228), 2001.
DOI : 10.1109/CDC.2001.980345

A. Mhamdi and W. Marquardt, A regularization approach to state estimation using observers, Proceedings of the 2001 American Control Conference. (Cat. No.01CH37148), pp.4228-4233, 2001.
DOI : 10.1109/ACC.2001.945641