TY  - RPRT
TI  - Letter Circular 531: photography and its applications (revision of Letter Circular 332)
PY  - 1938
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 531r1938
DO  - 10.6028/NBS.LCIRC.531r1938
ER  -