BibTex format
@unpublished{Bartelsman:2008,
author = {Bartelsman, EJ and Haskel, J and Martin, R},
title = {Distance to Which Frontier? Evidence on Productivity Convergence from International Firm-level Data},
url = {http://ideas.repec.org/p/cpr/ceprdp/7032.html},
year = {2008}
}