Columbia subject headings:
Harvard subject headings:
Quality of life--Canada
Quality of life--United States
Single people--Canada.
Single people--Mental health--Canada.
Single people--Mental health--United States.
Single people--United States
Princeton subject headings:
Quality of life--Canada.
Quality of life--United States.
Single people--Canada.
Single people--Mental health--Canada.
Single people--Mental health--United States.
Single people--United States.