TY  - RPRT
TI  - Letter Circular 280: measurement of the frequency of distant radio transmitting stations (replacing Letter Circular 171)
PY  - 1930
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 280
DO  - 10.6028/NBS.LCIRC.280
ER  -