TY  - RPRT
TI  - Letter Circular 769: spectral-transmissive properties and use of colored eye-protective glasses (supplementary to Letter Circular 421)
PY  - 1944
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 769
DO  - 10.6028/NBS.LCIRC.769
ER  -