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

Puerto Rico GPS Network - HUPR-University of Puerto Rico Humacao Campus P.S.
Start: 01-Jul-2015
End: 14-Nov-2022
Lopez, Alberto, 2016, Puerto Rico GPS Network - HUPR-University of Puerto Rico Humacao Campus P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T5S46QQQ