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

CVO GPS Network - 34SO-34SO P.S.
Start: 13-Mar-2015
End: 29-Apr-2016
Lisowski, Michael, 2017, CVO GPS Network - 34SO-34SO P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5ZS2TWS