@unpublished{Crawford2004,
author = {Ian Crawford},
title = {Necessary and sufficient conditions for latent separability},
year = {2004},
month = {Jun},
volume = {pp.},
doi = {10.1920/wp.ifs.2004.0417},
issn = {1742-0415},
url = {http://cemmap.ifs.org.uk/wps/cwp0402.pdf},
}