Update README.md

Author: sbryngelson

README.md

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 # Spectral Boundary Integral Solver for Cell-scale Flows
 ## Authors: S. H. Bryngelson, H. Zhao, A. Isfahani, J. B. Freund
 
-RBC3D is a flow solver for soft capsules and cells. It solves the boundary integral form of the Stokes equations via an algorithm tailored for cell-scale simulations:
+RBC3D is a flow solver for soft capsules and cells. 
+It implements the methods discussed in [Zhao et al., JCP (2010)](https://doi.org/10.1016/j.jcp.2010.01.024) and more.
+In particular, it solves the boundary integral form of the Stokes equations via an algorithm tailored for cell-scale simulations:
 
 * Spectrally-accurate spherical harmonics represent the deforming surfaces
 * Modified Green’s function approximation used for near-range interactions