TY - JOUR AU - Heavner, Thomas AU - Jefferts, Steven AU - Donley, Elizabeth AU - Shirley, Jon AU - Parker, Tom C2 - Metrologia DA - 2005-09-13 00:09:00 LA - en M1 - 42 PB - Metrologia PY - 2005 TI - NIST F1: Recent improvements and a resulting accuracy of δf/f=0.53x10-15 UR - https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=50098 ER -