@unpublished{Christensen2007,
author = {Mette Christensen},
title = {Heterogeneity in consumer demands and the income effect: evidence from panel data},
year = {2007},
month = {Sep},
doi = {10.1920/wp.ifs.2007.0716},
issn = {1742-0415},
url = {http://www.ifs.org.uk/wps/wp1607.pdf},
}