This book presents the basic concepts and recent developments of linear control problems with perturbations. The presentation concerns both continuous and discrete dynamical systems. It is self-contained and illustrated by numerous examples.
From the contents:

• Notion of state observers
• Observability
• Observers of full-phase vectors for fully determined linear systems
• Functional observers for fully determined linear systems
• Asymptotic observers for linear systems with uncertainty
• Observers for bilinear and discrete systems