TY  - RPRT
TI  - Letter Circular 398: publications on colorimetry and spectrophotometry from the National Bureau of Standards (superseding Letter Circular 273)
PY  - 1934
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 398
DO  - 10.6028/NBS.LCIRC.398
ER  -