TY  - RPRT
TI  - Circular of the Bureau of Standards no. 33 2nd edition: United States government specification for Portland cement
PY  - 1913
PB  - National Bureau of Standards
CY  - Gaithersburg, MD
SN  - NBS CIRC 33e2
DO  - 10.6028/NBS.CIRC.33e2
ER  -