Added reference

README.md

@@ -4,6 +4,13 @@ This repository contains the PCP Notebooks, which introduce some basic material
 
 If a static view of the PCP notebooks is enough for you, the [exported HTML versions](https://www.audiolabs-erlangen.de/PCP) can be used right away without any installation. All material including the explanations, the figures, and the audio examples can be accessed by just following the **HTML links**. If you want to **execute** the Python code cells, you have to clone/download the notebooks (along with the data), create an environment, and start a Jupyter server. You then need to follow the **IPYNB links** within the Jupyter session. The necessary steps are explained in detail in the [PCP notebook on how to get started](https://www.audiolabs-erlangen.de/resources/MIR/PCP/PCP_getstarted.html).
 
+## Reference
+
+If you use the PCP Notebooks in your teaching or research, please consider the following reference.
+
+Meinard Müller and Sebastian Rosenzweig.
+[PCP Notebooks: A Preparation Course for Python with a Focus on Signal Processing.](https://) Journal of Open Source Education (JOSE), ?(??), 202?.
+
 ## Installing Local Environment for Executing PCP Notebooks
 This is the preferred and tested variant for using the PCP notebooks.