diff --git a/kwarc.bib b/kwarc.bib
index 7580caddd..4257a242a 100644
--- a/kwarc.bib
+++ b/kwarc.bib
@@ -46121,6 +46121,15 @@ @string{kpmessage
 @STRING{stexyear = 2024}
 @STRING{testing = 16}
 
+@online{Betzendahl:proposal:20,
+  author = {Jonas Betzendahl},
+  title = {Undefinedness and Soft Typing in Formal Mathematics},
+  note = {Ph.D. proposal, Computer Science, FAU Erlangen-Nürnberg},
+  url = {https://gl.kwarc.info/supervision/proposal-archive/-/blob/master/2020/phd_proposal_jbetzendahl.pdf},
+  year = {2020},
+  pubs = {jbetzendahl}
+  }
+  
 @unpublished{KohSch:rlotm24,
  title = {Reusing Learning Objects via Theory Morphisms},
  author = {Michael Kohlhase and Marcel Sch{\"u}tz},