1. O.H. Zinke and W.F. Schmidt, in IEEE Transactions on Magnetics 29, (1993), p 2207–2212.
2. O.H. Zinke, USA Patent #4,901,017 (February 13, 1990).
3. O.H. Zinke, Canadian Patent #1296061 (February 18, 1992).
4. O.H. Zinke, European Common Market Patent #0329781 (March 29, 1995).
5. W.F. Schmidt and O.H. Zinke, in Review of Progress in QNDE, Vol. 12, (Plenum, New York, 1993) p. 1885.