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

Alaska Volcano Observatory GPS Network Okmok - OKSO-Okmok South P.S.
Start: 01-Sep-2004
End: 24-Sep-2022
Freymueller, Jeffrey T., Grapenthin, Ronni, 2005, Alaska Volcano Observatory GPS Network Okmok - OKSO-Okmok South P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5FQ9V0V