TY - CONF AU - Thomas Parker C2 - Proceedings of the 2011 Joint IEEE International Frequency Control Symposium and European Frequency and Time Forum, San Francisco, CA DA - 2011-07-31 LA - en PB - Proceedings of the 2011 Joint IEEE International Frequency Control Symposium and European Frequency and Time Forum, San Francisco, CA PY - 2011 TI - Update on a Comparison of Cesium Fountain Primary Frequency Standards ER -