Armstrong, Mark (contributor); Chen, Yongmin (contributor) - 2007
-RiversideandUniversityofTexas-Austinforusefulcomments.
Armstrong is grateful to the Economic and Social Research Council (UK) for funding assistance.
†Department of Economics …, University College London, Gower Street, London WC1E 6BT, UK.
Email: mark.armstrong@ucl.ac.uk.
‡Department of Economics …