L. Grune et al., Asymptotic stability equals exponential stability, and ISS equals finite energy gain - if you twist your eyes, SYST CONTR, 38(2), 1999, pp. 127-134
In this paper we show that uniformly global asymptotic stability for a fami
ly of ordinary differential equations is equivalent to uniformly global exp
onential stability under a suitable nonlinear change of variables. The same
is shown for input-to-state stability and input-to-state exponential stabi
lity, and for input-to-state exponential stability and a nonlinear H-infini
ty estimate. (C) 1999 Elsevier Science B.V. All rights reserved.