Loop-Stick References
V.S. Grechishkin
NQR Device for detecting plastic explosives, mines, and drugs.
Appl. Phys., A55:505-507 (1992).

M.C.K.Wiltshire, J.B. Pendry, I.R. Young, D.J. Larkman, D.J. Gilderdale, J.V. Hajnal
Microstructured magnetic materials for RF flux guides in magnetic resonance imaging.
Science, 291:849-851 (2001).