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

Long Valley L1 GPS Network - CAL1-CAL1 P.S.
Start: 27-Oct-1998
End: 22-Aug-1999
Dzurisin, Daniel, 2001, Long Valley L1 GPS Network - CAL1-CAL1 P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5KH0KMC