Add reference to smoothing (#56)

docs/src/interactive-api.md

@@ -112,7 +112,8 @@ type to `LinearAndCrossbarSpring`, and number of iterations = 25.
 These are generally good enough for most purposes.
 The most likely parameter to change is the number of iterations.
 Further details on the smoothing strategy and how it works are available
-[in the documentation](https://trixi-framework.github.io/HOHQMesh/the-control-input/#the-smoother).
+[in the documentation](https://trixi-framework.github.io/HOHQMesh/the-control-input/#the-smoother)
+and in [Minoli2011](https://www.sciencedirect.com/science/article/pii/S0021999110006534?via%3Dihub).
 
 To change the defaults, the smoother parameters can be set/enquired with the functions
 ```
@@ -482,4 +483,4 @@ To find out what the next actions are, use
 Finally, to clear the undo stack, use
 ```
    [Return:nothing] clearUndoRedo()
-```
+```