TY  - RPRT
TI  - Letter Circular 40: radio publications of the Bureau of Standards
PY  - 1923
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 40r11/1923
DO  - 10.6028/NBS.LCIRC.40r11/1923
ER  -