Zu-Qing Qu, Springer, 2004, Model Order Reduction Techniques: with Applications in Finite Element Analysis
I have read this book during my work at IMTEK. It is a nice introduction into the engineering world of model reduction: modal superposition, Guyan reduction, and different variants of dynamic condensation (CMS). Some methods are already for long time implemented in the commercial software.
However in parallel it would be good to compare this book with Antoulas’ book
The latter introduces model reduction from the viewpoint of mathematicians. Interestingly enough these two worlds of model reduction do not cross over. Engineers usually do not know about modern model reduction developed by mathematicians, on the other hand mathematicians do not want to compare their method with those developed by engineers.
Well, engineering methods are working only for structural mechanics, they just do not work for other domains. Still it would be interesting to see more works that would explain why these method are working at least for structural dynamics.