TY  - RPRT
TI  - Circular of the Bureau of Standards no. 552 2nd edition: standard samples- a catalog of reference materials issued by the National Bureau of Standards
PY  - 1957
PB  - National Bureau of Standards
CY  - Gaithersburg, MD
SN  - NBS CIRC 552e2
DO  - 10.6028/NBS.CIRC.552e2
ER  -