Columbia subject headings:
Electromagnetic fields--United States--Measurement.
Electromagnetism--Physiological effect.
Magnetic fields--Measurement.
Harvard subject headings:
Electromagnetic fields--United States--Measurement.
Electromagnetism--Physiological effect
Magnetic fields--Measurement.
Princeton subject headings:
Electromagnetic fields--United States--Measurement.
Electromagnetism--Physiological effect.
Magnetic fields--Measurement.