TY  - RPRT
TI  - Levels of illumination and legibility 
AU  - Yonemura, Gary T
AU  - Benson, William M
AU  - Tibbott, Robert
PY  - 1977
PB  - National Bureau of Standards
CY  - Gaithersburg, MD
SN  - NBS IR 77-1306
DO  - 10.6028/NBS.IR.77-1306
ER  -