TY  - RPRT
TI  - Spectrophotometric and colorimetric study of color transparencies of some natural objects 
AU  - Keegan, Harry J
AU  - Haas, Gladys M
AU  - Hall, Wiley A, Jr
PY  - 1957
PB  - National Bureau of Standards
CY  - Gaithersburg, MD
SN  - NBS RPT 4794
DO  - 10.6028/NBS.RPT.4794
ER  -