Alexandra Y. Aikhenvald is a Distinguished Professor and Research Leader at the Cairns Institute, James Cook University, Australia. Her books include Classifiers: a Typology of Noun Categorization Devices (2000, paperback 2003), Language Contact in Amazonia (2002), Evidentiality (2004, paperback 2006), The Manambu Language from East Sepik, Papua New Guinea (2008), Imperatives and Commands (2010), and The Languages of the Amazon (2012), all published by OUP. R. M. W. Dixon is Adjunct Professor at the Cairns Institute, James Cook University, Australia. His books include Australian Languages: Their Nature and Development (CUP 2002), The Jarawara Language of Southern Amazonia (OUP 2004), winner of the 2004-5 Leonard Bloomfield Prize, A Semantic Approach to English Grammar (2nd edn OUP 2005), and Basic Linguistic Theory, volumes 1-3 (OUP 2010-12).