TY  - RPRT
TI  - Letter Circular 704: optical instruments, refractometry and optical properties of glass (supersedes Letter Circular 673)
PY  - 1942
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 704
DO  - 10.6028/NBS.LCIRC.704
ER  -