TY  - RPRT
TI  - Letter Circular 672: electrical measuring instruments, meters and their accessories (superseding Letter Circular 554, 364, and 233)
PY  - 1941
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 672
DO  - 10.6028/NBS.LCIRC.672
ER  -