Columbia subject headings:
Families--United States.
Family life surveys--United States.
Widowers--United States--Longitudinal studies.
Widows--United States--Longitudinal studies.
Harvard subject headings:
Families--United States.
Family life surveys--United States.
Widowers--United States--Longitudinal studies.
Widows--United States--Longitudinal studies.
Princeton subject headings:
Families--United States.
Family life surveys--United States.
Widowers--United States--Longitudinal studies.
Widows--United States--Longitudinal studies.