Quantiles, Corners, and the Extensive Margin of Trade
José Machado, João Santos Silva, Kehai Wei
European Economic Review, vol. 89, 2016, p. 73-84.

Estimating the Extensive Margin of Trade
João Santos Silva, Silvana Tenreyro, Kehai Wei
Journal of International Economics, vol. 93, 2014, p. 67-75.