diff --git a/doc/conf.py b/doc/conf.py
index 42b96855..83831054 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -52,8 +52,8 @@ extensions = [
 autodoc_default_flags = ["members"]
 autosummary_generate = True
 
-bibtex_bibfiles = ['publications.bib']
-bibtex_default_style = 'unsrt'
+bibtex_bibfiles = ["publications.bib"]
+bibtex_default_style = "unsrt"
 
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ["_templates"]
diff --git a/doc/publications.bib b/doc/publications.bib
index e91848cd..f8f7b6ca 100644
--- a/doc/publications.bib
+++ b/doc/publications.bib
@@ -1,3 +1,9 @@
+@Comment{
+SPDX-FileCopyrightText: 2023 2023, The PyPSA-Eur authors
+
+SPDX-License-Identifier: CC-0
+}
+
 @article{PyPSAEur,
     author = "Jonas Hörsch and Fabian Hofmann and David Schlachtberger and Tom Brown",
     title = "PyPSA-Eur: An open optimisation model of the {European} transmission system",
diff --git a/doc/publications.rst b/doc/publications.rst
index f87849d3..c824873e 100644
--- a/doc/publications.rst
+++ b/doc/publications.rst
@@ -8,4 +8,4 @@ Publications
 ##########################################
 
 .. bibliography::
-   :all:
\ No newline at end of file
+   :all: