TY - GEN AU - Kathryn Stephenson C2 - , National Institute of Standards and Technology, Gaithersburg, MD DA - 2019-02-01 05:02:00 DO - https://doi.org/10.6028/NIST.IR.8261-02 LA - en PB - , National Institute of Standards and Technology, Gaithersburg, MD PY - 2019 TI - NIST time and frequency bulletin::February ER -