TY  - RPRT
TI  - Letter Circular 687: alphabetical list of simplified practice recommendations (supersedes Letter Circular 670)
PY  - 1942
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 687r1942
DO  - 10.6028/NBS.LCIRC.687r1942
ER  -