WH Goldstein, Zigler, A , Burkhalter, PG , Nagel, DJ , Bar-Shalom, A , Oreg, J , Luk, TS , McPherson, A , and Rhodes, CK . 1993. “X-Ray Emission From A 650-Fs Laser-Produced Barium Plasma”. Physical Review E, 47, Pp. 4349.