@article{Llewellyn2009,
author = {David Llewellyn and Iain Lang and Kenneth Langa and Felix Naughton and Fiona Matthews},
title = {Exposure to secondhand smoke and cognitive impairment in non-smokers: national cross-sectional study with cotinine measurement},
journal = {British Medical Journal},
year = {2009},
month = {Feb},
volume = {12},
number = {1},
pages = {338-462},
url = {http://www.bmj.com/cgi/content/abstract/338/feb12_2/b462},
}