@unpublished{Clark2001,
author = {Tom Clark and Julian McCrae},
title = {Issues arising in tax and benefit modelling: the case of family credit},
year = {2001},
month = {Jun},
doi = {10.1920/wp.ifs.2001.0117},
issn = {1742-0415},
url = {http://www.ifs.org.uk/wps/wp0117.pdf},
}