CONTRIBUTORS

--- a/CONTRIBUTORS	Mon Jun 18 14:22:26 2018 +0100
+++ b/CONTRIBUTORS	Mon Jun 18 15:56:03 2018 +0100
@@ -6,6 +6,9 @@
 Contributions to Isabelle2018
 -----------------------------
 
+* June 2018: Martin Baillon and Paulo Emílio de Vilhena
+  A variety of contributions to HOL-Algebra.
+
 * May 2018: Manuel Eberl
   Landau symbols and asymptotic equivalence (moved from the AFP).