diff --git a/bibliography.bib b/bibliography.bib
index ec767dd..7a6d626 100644
--- a/bibliography.bib
+++ b/bibliography.bib
@@ -133,4 +133,10 @@
     urldate = {24.04.2025},
     url = {https://www.ava-altenrhein.ch/kanalnetz/entwaesserungssysteme/},
     howpublished = {https://www.ava-altenrhein.ch/kanalnetz/entwaesserungssysteme/},
+}
+
+@booklet{ingenieurshandbuch_hoerler_1966,
+    author = {Arnold Hörler},
+    title = {Kanalisation, Sonderdruck aus dem Ingenieurhandbuch Band II},
+    date = {1966},
 }
\ No newline at end of file