Update README.md

Author: OpenRealTimeSimulation

README.md

@@ -35,7 +35,11 @@ Solver C++ Code Generation Tools are licensed under the GNU General Public Licen
 
 ## Literature 
 
-The ORTiS solver code generation tools were first presented in:
+The ORTiS solver code generation tools themselves are presented in:
+
+* M. Milton and A. Benigni, "ORTiS solver codegen: C++ code generation tools for high performance, FPGA-based, real-time simulation of power electronic systems," SoftwareX, vol. 13, Jan. 2021.
+doi: 10.1016/j.softx.2021.100660
+url: https://www.sciencedirect.com/science/article/pii/S2352711021000054
 
 * M. Milton and A. Benigni, "Software and Synthesis Development Libraries for Power Electronic System Real-Time Simulation," *2019 IEEE Electric Ship Technologies Symposium (ESTS)*, Arlington VA, 2019, pp. 368-376, Aug. 2019.
 doi: 10.1109/ESTS.2019.8847940