Higher-order contributions observed in three-dimensional (e, 2e) cross-section measurements at 1-keV impact energy - Durr, M.; Dimopoulou, C.; Najjari, B.; Dorn, A.; Bartschat, K.; Bray, Igor; Fursa, Dmitry; Chen, Z.; Madison, D.; Ullrich, J. (American Physical Society, 2008)