TY - RPRT TI - Supplement to National Bureau of Standards Circular no. 583: x-ray attenuation coefficients from 10 kev to 100Mev AU - McGinnies, Rosemary T PY - 1959 PB - National Bureau of Standards CY - Gaithersburg, MD SN - NBS CIRC 583sup DO - 10.6028/NBS.CIRC.583sup ER -