TY - GEN AU - Davis, R S C2 - , National Institute of Standards and Technology, Gaithersburg, MD DA - 1989-01-01 05:01:00 DO - https://doi.org/10.6028/NIST.SP.250-31 LA - en PB - , National Institute of Standards and Technology, Gaithersburg, MD PY - 1989 TI - Mass calibrations: ER -