RT Journal Article SR Electronic T1 Collecting information on marital status: a methodological note JF Journal of Epidemiology and Community Health JO J Epidemiol Community Health FD BMJ Publishing Group Ltd SP 175 OP 176 DO 10.1136/jech.56.3.175 VO 56 IS 3 A1 G Barrett A1 K Wellings YR 2002 UL http://jech.bmj.com/content/56/3/175.abstract AB