TY  - RPRT
TI  - Time & frequency bulletin No. 391 
AU  - Bennett, Gwen E
PY  - 1990
PB  - National Institute of Standards and Technology
CY  - Gaithersburg, MD
SN  - NIST IR 90-3940-6
DO  - 10.6028/NIST.IR.90-3940-6
ER  -