TY  - RPRT
TI  - Letter Circular 780: methods of using standard frequencies broadcast by radio (supersedes Letter Circular 751)
PY  - 1945
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 780
DO  - 10.6028/NBS.LCIRC.780
ER  -