Most used for library research inquiries :
GeoScienceWorld https://pubs.geoscienceworld.org/
Zenodo, MODFLOW search https://zenodo.org/search?q=MODFLOW&l=list&p=1&s=10&sort=newest
Québec https://www.environnement.gouv.qc.ca/eau/souterraines/index.htm
France https://www.brgm.fr/fr/etat-nappes-eau-souterraine-suivi-assure-brgm
Australia https://www.ga.gov.au/scientific-topics/water/groundwater
Princeton University Library, example print collection, China
China, weather modification publications from 1972 to 2020
China, Geochemical atlases
How-to's Examples
2012 - On-line access to geoscience bibliographic citations
https://pubs.usgs.gov/publication/70037963
2001 - Online Bibliographic Sources in Hydrology
https://www.tandfonline.com/doi/abs/10.1300/J122v21n03_05 & https://pubs.usgs.gov/publication/70023512
Hydrogeology Bibliography Examples
2011 - Review and interpretation of previous work and new data on the hydrogeology of the Schwartzwalder Uranium Mine and vicinity, Jefferson County, Colorado
https://pubs.usgs.gov/publication/ofr20111092
2002 - Bibliography on the Occurrence and Intrusion of Saltwater in Aquifers along the Atlantic Coast of the United States
https://pubs.usgs.gov/of/2002/ofr02235/
Example Sources
USGS Publications https://pubs.usgs.gov/
Techniques & Methods
https://pubs.usgs.gov/browse/Report/USGS%20Numbered%20Series/Techniques%20and%20Methods/
Techniques of Water-Resources Investigations
USGS Library https://www.usgs.gov/programs/usgs-library
USGS MODFLOW https://pubs.usgs.gov/search?q=MODFLOW
USGS ScienceBase search, MODFLOW https://www.sciencebase.gov/catalog/items?q=MODFLOW
USGS Mineral Resources Online Spatial Data https://mrdata.usgs.gov/
USGS National Uranium Resource Evaluation (NURE) program, Hydrogeochemical and stream sediment reconnaissance (HSSR)
- email Emily ( ewild@princeton.edu ) for pdfs of NURE-HSSR reports, I am working on uploading a publicly available digital archive of the print reports and microfiche