1. W.K. Chu, K.B. Ma and C.K. McMichael, U.S. Patent #5, 159,219.
2. 10th Anniversary HTS Workshop on Physics, Materials and Applications;Xia,1996
3. Proceedings of the 1998 Applied Superconductivity Conference;Yu,1998
4. W.K. Chu, K.B. Ma, J.H. Yu, Q.Y. Chen, E. Lee, and Y. Postrekhin, U.S. patent pending.
5. Proceedings of the Fourth International Symposium on Magnetic Bearings;Mizuno,1994