Some links related to Identification
Comparing DSR with other methods.
Sotomayor et al
"Multivariable identification of an activated sludge process with subspace-based algorithms"
Modeling, Identification and Control (MIC)
-Linkoping University (Publications from Ljung among others)
Perspectives in System Identification.
state estimate equation
Kalman filter applications
A Dynamic Positioning System Based on Kalman Filtering and Optimal Control
David Di Ruscio