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

Montserrat GPS Network - SOUF-Soufriere Hills P.S.
Start: 16-Mar-1999
End: 15-Oct-1999
Mattioli, Glen, 2004, Montserrat GPS Network - SOUF-Soufriere Hills P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5ST7N6F