1. L.D. Arnold, X. Chen, H. Dong, A. Garton, M.J. Mulvihill, C.P.S. Smith, G.H. Thomas, T.M. Krulle, J. Wang, US Patent 20070208053 (2007).
2. P.J. Cox, T.N. Majid, S. Amendola, S.D. Deprets, C. Edlin, J.Y.Q. Lai, A.D. Morley, US Patent 20040198737 (2004).
3. M. Klein, US Patent 20110166175 (2011).
4. H.J. Dyke, S. Price, K. Williams, US Patent 20100216768 (2010).
5. G.N. Anilkumar, S.B. Rosenblum, S. Venkatraman, F.G. Njoroge, J.A. Kozlowski, US Patent 20100239527 (2010).