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

Afar GPS Network - DA35-Digdiga P.S.
Start: 14-Jan-2006
End: 03-Nov-2009
Calais, Eric, 2007, Afar GPS Network - DA35-Digdiga P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5SN071V