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

MAGNET - GIRL-Girl's Farm P.S.
Start: 30-Mar-2013
End: 14-Dec-2021
Blewitt, Geoff, Hammond, William C., Kreemer, Corne, 2013, MAGNET - GIRL-Girl's Farm P.S., UNAVCO, GPS/GNSS Observations Dataset, 
https://doi.org/10.7283/T50P0X6K