Time and Frequency from A to Z. Phase. Nist (National Institute of Standards and Technology (NIST)). 2010-05-12 [12 June 2016]. (原始内容存档于2016-08-16). This content has been copied and pasted from an NIST web page and is in the public domain.
Time and Frequency from A to Z. Phase. Nist (National Institute of Standards and Technology (NIST)). 2010-05-12 [12 June 2016]. (原始内容存档于2016-08-16). This content has been copied and pasted from an NIST web page and is in the public domain.