@INPROCEEDINGS{ist:montenbruck16d, author = {Montenbruck, J. M. and Allg{\"o}wer, F.}, title = {Persistence of Excitation and the Feedback Theorem for Passive Systems}, booktitle = {Proc.\ 10th IFAC Symp.\ Nonlinear Control Systems (NOLCOS)}, year = {2016}, pubtype = {proceeding} }