TY  - RPRT
TI  - Letter Circular 993: standardization of pH measurements made with glass electrode (supersedes Letter Circular 933)
PY  - 1950
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - LCIRC 993
DO  - 10.6028/NBS.LCIRC.993
ER  -