diff -r 615233977155 -r 1f163f772da3 CONTRIBUTORS
--- a/CONTRIBUTORS	Sun Apr 14 12:00:17 2019 +0100
+++ b/CONTRIBUTORS	Sun Apr 14 13:32:26 2019 +0100
@@ -6,6 +6,12 @@
 Contributions to Isabelle2019
 -----------------------------
 
+* April 2019: LC Paulson
+  Homology and supporting lemmas on topology and group theory
+
+* April 2019: Paulo de Vilhena and Martin Baillon
+  Group theory developments towards proving algebraic closure
+
 * February/March 2019: Makarius Wenzel
   Stateless management of export artifacts in the Isabelle/HOL code generator.