TY - JOUR PB - American Physical Society ID - 10.1103/PhysRevFocus.13.13 TI - A Constant Worthy of the Name JF - Physical Review Focus JA - Phys. Rev. Focus J1 - FOCUS VL - 13 IS - SP - 13 EP - PY - 2004/03/31/ UR - http://link.aps.org/doi/10.1103/PhysRevFocus.13.13 A1 - Monroe, Don ER -