TY  - RPRT
TI  - Circular of the Bureau of Standards no. 454: proving rings for calibrating testing machines
AU  - Wilson, Bruce L
AU  - Tate, Douglas R
AU  - Borkowski, George
PY  - 1946
PB  - National Bureau of Standards
CY  - Gaithersburg, MD
SN  - NBS CIRC 454
DO  - 10.6028/NBS.CIRC.454
ER  -