diff --git a/StageSonification2012.bib b/StageSonification2012.bib
index beee1c3..9f42b5e 100644
--- a/StageSonification2012.bib
+++ b/StageSonification2012.bib
@@ -323,4 +323,9 @@
 	publisher = {Dover Publications},
 	author = {Isenberg, Cyril},
 	year = {1992}
+},
+
+@misc{drenckhan_presentation_????,
+	title = {A presentation on liquid foams},
+	author = {Drenckhan, Wiebke}
 }
\ No newline at end of file