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

Greenland GNSS Network - SMM1-Summit Camp, Greenland P.S.
Start: 02-Jul-2009
End: 07-Jul-2013
UNAVCO Community, 2009, Greenland GNSS Network - SMM1-Summit Camp, Greenland P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T52N511R