1 A.D. Bristow, D.. Karaiskaj, X.. Dai, T.. Zhang, C.F. Carlsson, K.R. Hagen, R.. Jimenez, and S.T. Cundiff, Rev. Sci. Instrum. 80, (2009).
1 E.. Gagnon, A.S. Sandhu, A.J. Paul, K.R. Hagen, A.. Czasch, T.. Jahnke, P.. Ranitovic, C.L. Cocke, B.C. Walker, M.. Murnane, and H.. Kapteyn, Review of Scientific Instruments 79, (2008).