TY - JOUR AU - David Hummer BT - The Astrophysical Journal DA - Jan-10-1964 DO - 10.1086/147914 PY - 1964 EP - 276 T2 - The Astrophysical Journal TI - The Mean Number of Scatterings by a Resonance-Line Photon UR - http://adsabs.harvard.edu/full/1964ApJ...140..276H VL - 140 SN - 0004-637X ER -