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

Southern Basin and Range GPS Network - LITT-Little Skull Mountain P.S.
Start: 27-Jan-1999
End: 22-Oct-2022
Wernicke, Brian P., 1999, Southern Basin and Range GPS Network - LITT-Little Skull Mountain P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T54X564J