http://www.saelig.com/product/PSBEA014.htm
http://www.tti-test.com/go/iprober/index.htm
http://www.sensorsmag.com/sensors-mag/cambridge-university-researchers-microfabricate-fluxgate-mag-894
A full review of the AIM/TTi I-Prober 520 Positional Current Probe.
Some theory on how fluxgate magnetometers work.
Measuring the absolute value of Earth's magnetic field
And a practical example of ground plane current tracing.
