TY  - RPRT
TI  - NIST time and frequency bulletin, no.521 
AU  - Bennett, Gwen E
PY  - 2001
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - NIST IR 6604-04
DO  - 10.6028/NIST.IR.6604-04
ER  -