TY  - RPRT
TI  - Letter Circular 1023: standard frequencies and time signals WWV and WWVH (supersedes Letter Circular 1009)
PY  - 1956
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 1023
DO  - 10.6028/NBS.LCIRC.1023
ER  -