Mathias S., C. La-O-Vorakiat, P. Grychtol, J.M. Shaw, R. Adam, H.T. Nembach, M.E. Siemens, S. Eich, C.M. Schneider, T.J. Silva, and M. Aeschlimann, Pnas109, 4792-4797(2012).
La-O-Vorakiat C., M.E. Siemens, M. Murnane, H. Kapteyn, P. Grychtol, R. Adam, C.M. Schneider, J.M. Shaw, H.T. Nembach, and T.J. Silva, Physical Review Letters103, (2009).
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