1. California State University Long Beach. 2018. Gray Literature.
https://csulb.libguides.com/graylit
2. Colorado State University Libraries. Water Resources: Important Databases for Water Resources.
http://libguides.colostate.edu/c.php?g=64776&p=416557
3. Comparisons of reference manager software.
https://en.wikipedia.org/wiki/Comparison_of_reference_management_software
4. Mendeley. 2018. Videos and Tutorials.
https://www.mendeley.com/guides/videos
5. National Service Center for Environmental Publications:
https://www.epa.gov/nscep