TY  - RPRT
TI  - Circular of the Bureau of Standards no. 25 6th edition: standard samples- general information
PY  - 1917
PB  - National Bureau of Standards
CY  - Gaithersburg, MD
SN  - NBS CIRC 25e6
DO  - 10.6028/NBS.CIRC.25e6
ER  -