Added preliminary license section to the readme file.

README.md

@@ -7,7 +7,12 @@ Compute linear mode conversion of RF waves in plasmas using ray tracing and ray
 
 For details about the ray splitting algorithm for computing linear mode conversion of RF waves, see:
 
+* E. R. Tracy, A. N. Kaufman, and A. Jaun. A ray-based algorithm for multi-dimensional linear conversion. *Physics Letters A*, **290**(5-6):309–316, 2001.
 * A. Jaun, E. R. Tracy, and A. N. Kaufman. Eikonal waves, caustics and mode conversion in tokamak plasmas. *Plasma Physics and Controlled Fusion*, **49**(1):43–67, 2007.
-* E. R. Tracy, A. N. Kaufman, and A. Jaun. A ray-based algorithm for multi-dimensional linear conversion. *Physics Letters A*, **290**(5-6):309–316, 2001.* E. R. Tracy, A. N. Kaufman, and A. Jaun. Local fields for asymptotic matching in multidimensional mode conversion. *Physics of Plasmas*, **14**(8):082102, 2007.
+* E. R. Tracy, A. N. Kaufman, and A. Jaun. Local fields for asymptotic matching in multidimensional mode conversion. *Physics of Plasmas*, **14**(8):082102, 2007.
 
-To get started using this code, open and run `main.m`.
+To get started using this code, open and run `main.m`.
+
+# License #
+
+You may use it and modify this code with the same terms that are generally accepted in the GNU license; if relevant, it would of course be nice if you tell us about potential bugs that you find and if you properly cite the literature that has been produced by the group to document the team work that resulted in this development.