The following information obtained from UNAVCO's online DOI system:
(https://www.unavco.org/data/doi/search/search.html)

SCIGN USGS GPS Network - PHLB-Philips Lab P.S.
Start: 24-Jan-2000
End: 10-Jul-2019
Hudnut, Kenneth, King, Nancy, Aspiotes, Aris G., Borsa, Adrian A., Determan, Daniel N., Galetzka, John E., Stark, Keith F., 2005, SCIGN USGS GPS Network - PHLB-Philips Lab P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5MG7MSN