TY  - RPRT
TI  - Letter Circular 658: radio distance ranges, summer 1941 and winter 1941-42 (supersedes Letter Circular 615)
PY  - 1941
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 658
DO  - 10.6028/NBS.LCIRC.658
ER  -