Fourth-Order Vacuum Polarization Correction to the Positronium Hyperfine Structure
David A. Owen
Phys. Rev. Lett. 30, 887 (1973) - Published 7 May, 1973
High-Resolution Study of Fluorine Metastable X-Ray Emitters
Patrick Richard, R. L. Kauffman, F. F. Hopkins, C. W. Woods, and K. A. Jamison
Phys. Rev. Lett. 30, 888 (1973) - Published 7 May, 1973