BibTex format
@unpublished{Martin:2009,
author = {Martin, M and de, Preux L},
publisher = {NBER Working Paper, CEP Working Paper},
title = {The Impacts of the Climate Change Levy on business: Evidence from Microdata},
url = {http://cep.lse.ac.uk/pubs/download/dp0917.pdf},
year = {2009}
}