TY - JOUR AU - Steven Fick C2 - Journal of Research of the National Institute of Standards and Technology DA - 2008-10-01 LA - en M1 - 113 PB - Journal of Research of the National Institute of Standards and Technology PY - 2008 TI - Long-term Stability of the NIST Standard Ultrasonic Source UR - https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=824662 ER -