Sanfelice R.G, Praly L..  2012.  Convergence of Nonlinear Observers on $\mathbb{R}^n$ with a {R}iemannian Metric {(Part I)}. IEEE Transactions on Automatic Control. 57:1709–1722.

Sanfelice R.G, Praly L..  2016.  Convergence of Nonlinear Observers on $\mathbbR^n$ with a Riemannian Metric (Part II). IEEE Transactions on Automatic Control. 61

Sanfelice R.G, Praly L..  2009.  Nonlinear Observer Design with an Appropriate {R}iemannian Metric. Proc. 48th IEEE Conference on Decision and Control and 28th Chinese Control Conference. :6514–6519.

Sanfelice R.G, Praly L..  2011.  On the Performance of High-gain Observers with Sign-indefinite Gain Adaptation under Measurement Noise. Automatica. 47:2165–2176.

Sanfelice R.G, Praly L..  2015.  Solution of a {R}iccati equation for the design of an observer contracting a {R}iemannian distance. Proceedings of the IEEE Conference on Decision and Control. :4996–5001.

Sanfelice R.G, Praly L..  2010.  A Technical Result for the Study of High-gain Observers with Nonmonotonic Dynamic Gain. Proc. NOLCOS 2010. :284–289.

Sanfelice R.G, Praly L..  2010.  A Technical Result for the Study of High-gain Observers with Sign-indefinite Gain Adaptation.