TY - JOUR PB - American Physical Society ID - 10.1103/PhysRevFocus.3.33 TI - Selecting Excited States JF - Physical Review Focus JA - Phys. Rev. Focus J1 - FOCUS VL - 3 IS - SP - 33 EP - PY - 1999/06/14/ UR - http://link.aps.org/doi/10.1103/PhysRevFocus.3.33 A1 - Anonymous, ER -