By executing the following Simulink model you can reproduce the Example 1 (Unified Chaotic System) of the above paper which is a free-short version of the journal paper:
"L. Torres, G. Besançon, D. Georges, C. Verde. "Exponential nonlinear observer for parametric identification and synchronization of chaotic systems", Mathematics and Computers in Simulations. Volume 82, Issue 5, Pages 836 – 846, 2012"
this material, please cite the journal version.