Columbia subject headings:
Automatic tracking--Congresses.
Target acquisition--Congresses.
Tracking radar--Congresses.
Harvard subject headings:
Automatic tracking--Congresses.
Target acquisition--Congresses.
Tracking radar--Congresses.
Princeton subject headings:
Balloons--Tracking--Congresses.
Guided missiles--Tracking--Congresses.
Optical detectors--Congresses.
Optical radar--Congresses.