TY - RPRT TI - Letter Circular 393: procedure for the measurement of the reflectance of manila rope fiber for light of wave length 500 millimicrons AU - Becker, Genevieve PY - 1933 PB - National Institute of Standards and Technology CY - Gaithersburg, MD SN - LCIRC 393 DO - 10.6028/NBS.LCIRC.393 ER -