TY  - RPRT
TI  - Radioactivity calibration standards 
AU  - Mann, W B
AU  - Garfinkel, S B
PY  - 1970
PB  - National Bureau of Standards
CY  - Gaithersburg, MD
SN  - NBS SP 331
DO  - 10.6028/NBS.SP.331
ER  -