Gradiometer References

H.B. Suits, A.N. Garroway
Optimizing surface coils and the self-shielded gradiometer.
Journal of Applied Physics, 94:4170-4178 (2003).

B.H. Suits, A.N. Garroway, J.B. Miller
Noise-imune coil for unshielded magnetic resonance measurements.
J. Magn. Reson., 131:154-158 (1998).