@unpublished{Choné2009,
author = {Philippe Choné and Guy Laroque},
title = {Negative marginal tax rates and heterogeneity},
year = {2009},
month = {May},
doi = {10.1920/wp.ifs.2009.0912},
url = {http://www.ifs.org.uk/wps/wp0912.pdf},
}