This E4D user guide can be cited with the following reference:
Johnson, TC, JR Robinson, SK White, Y Zue and P. Jaysaval. E4D User Guide, Pacific Northwest National Laboratory, 2020. http://www.pnnl.gov/e4d-userguide.
The primary technical reference for E4D is:
Johnson, TC, RJ Versteeg, A Ward, FD Day-Lewis & A Revil 2010. Improved hydrogeophysical characterization and monitoring through parallel modeling and inversion of time-domain resistivity and induced-polarization data. Geophysics, 75(4).
