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

CVO GPS Network - CVO1-CVO1 P.S.
Start: 04-Jan-2003
End: 26-May-2020
Lisowski, Michael, 2012, CVO GPS Network - CVO1-CVO1 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T54X55XF