Michael Barlow 
Situated Theory of Agreement (RLE Linguistics B: Grammar) [PDF ebook] 

Typical cases of agreement are easy to identify, but where the boundaries of agreement lie depend on what aspects of the agreement relation are considered to be defining properties. It is a short step from viewing agreement in the traditional way, as a matching of features, to defining agreement as any relation that ensures consistency of information in two separate structures. This book takes as its topic agreement as it is traditionally conceived, one that only involves morphosyntactic categories.