Aria Adli & Marco Garcia Garcia 
Variation in Language: System- and Usage-based Approaches [PDF ebook] 

Where is the locus of language variation? In the grammar, outside the grammar or somewhere in between? Taking up the debate between system- and usage-based approaches, this volume provides new discussions of fundamental issues of language variation. It includes several highly insightful theoretical contributions as well as innovative empirical studies considering different types of data, the role of priming in language change and rare phenomena.