also cite the WHAM paper that is referenced by the Grossfield code docs

Author: akohlmey

journal-article.bib

@@ -613,6 +613,18 @@ @article{kumar1992weighted
   publisher={Wiley Online Library}
 }
 
+@article{kumar1995multidim,
+  title =        {Multidimensional free-energy calculations using the
+                  weighted histogram analysis method},
+  author =       {Kumar, Shankar and Rosenberg, John M. and Bouzida,
+                  Djamal and Swendsen, Robert H. and Kollman, Peter A.},
+  journal =      {Journal of Computational Chemistry},
+  volume =       {16},
+  number =       {11},
+  pages =        {1339-1350},
+  doi =          {https://doi.org/10.1002/jcc.540161104},
+}
+
 @article{oostenbrink2004biomolecular,
   title={A biomolecular force field based on the free enthalpy of hydration and solvation: the {{GROMOS}} force-field parameter sets {{53A5}} and {{53A6}}},
   author={Oostenbrink, Chris and Villa, Alessandra and Mark, Alan E and van Gunsteren, Wilfred F},

lammps-tutorials.tex

@@ -3901,7 +3901,7 @@ \subsubsection{Method 2: Umbrella sampling}
 we apply a potential $V$ and force it to move along the $x$-axis. The chosen path
 is called the axis of reaction. Several simulations (called windows) will be
 conducted with varying positions for the center of the applied biasing. The results
-will be analyzed using the weighted histogram analysis method (WHAM)~\cite{kumar1992weighted},
+will be analyzed using the weighted histogram analysis method (WHAM)~\cite{kumar1992weighted,kumar1995multidim},
 which allows for the removal of the biasing effect and ultimately deduces the
 unbiased free energy profile.
 
@@ -4028,7 +4028,7 @@ \subsubsection{Method 2: Umbrella sampling}
 
 To generate the free energy profile from the particle positions
 saved in the \flecmd{umbrella-sampling.i.dat} files,
-we use the WHAM algorithm as implemented by Marc Grossfield~\cite{grossfieldimplementation}.
+we use the WHAM~\cite{kumar1992weighted,kumar1995multidim} algorithm as implemented by Marc Grossfield~\cite{grossfieldimplementation}.
 You can download it from \href{http://membrane.urmc.rochester.edu/?page_id=126}{Alan Grossfield}'s
 website.  The executable called \flecmd{wham} generated by following the instructions
 from the website must be placed next to \flecmd{umbrella-sampling.lmp}.  To apply