Add citation hint

Change-Id: I006177adbd841fa975805c13cd1b5b1c4f77b2d4
diff --git a/Readme.md b/Readme.md
index b898434..c96fe6d 100644
--- a/Readme.md
+++ b/Readme.md
@@ -91,6 +91,8 @@
 
 It is published under the [BSD-2 License](LICENSE).
 
+**To cite this work, …**<br>
+please refer to: Kupietz et al. (2020), below.
 ## Contributions
 
 Contributions are very welcome!