Columbia subject headings:
Ambulatory medical care--Utilization--United States--Statistics--Databases.
Ambulatory medical care--Utilization--United States--Statistics--Software.
Health surveys--United States--Databases.
National Ambulatory Medical Care Survey (U.S.)--Databases.
National Ambulatory Medical Care Survey (U.S.)--Software.
Physician services utilization--United States--Statistics--Databases.
Physician services utilization--United States--Statistics--Software.
United States--Statistics, Medical--Databases.
Harvard subject headings:
Ambulatory medical care--Utilization--United States--Statistics--Databases.
National Ambulatory Medical Care Survey (U.S.)--Databases.
Physician services utilization--United States--Statistics--Databases.
Princeton subject headings: