"Risk-sharing in federations: Theory and evidence" with Ahmed Saber Mahmud, Faruk Balli and Sumit Joshi, November 2015. "Does economic growth matter? Technology-push, demand-pull, and endogenous drivers of innovation in the renewable energy industry" with Sam Aflaki and Andrea Masini, May 2017. "Has the non-oil sector decoupled from oil sector? A case study of Gulf Cooperation Council countries"Unpublished, March 2010.