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

CVO GPS Network - SHRK-Shell Rock P.S.
Start: 18-Jul-2015
End: 14-Nov-2022
Lisowski, Michael, 2016, CVO GPS Network - SHRK-Shell Rock P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5377732