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 - OKCD-Okmok Cone D P.S.
Start: 27-Jul-2002
End: 17-Apr-2007
Freymueller, Jeffrey T., 2003, Alaska Volcano Observatory GPS Network Okmok - OKCD-Okmok Cone D P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5ZP44GV