diff --git a/elki-clustering/src/main/java/elki/clustering/hierarchical/linkage/GroupAverageLinkage.java b/elki-clustering/src/main/java/elki/clustering/hierarchical/linkage/GroupAverageLinkage.java
index 8f08191dc3..18748bb784 100644
--- a/elki-clustering/src/main/java/elki/clustering/hierarchical/linkage/GroupAverageLinkage.java
+++ b/elki-clustering/src/main/java/elki/clustering/hierarchical/linkage/GroupAverageLinkage.java
@@ -65,7 +65,7 @@
     title = "A statistical method for evaluating systematic relationship", //
     booktitle = "University of Kansas science bulletin 28", //
     url = "https://archive.org/details/cbarchive_33927_astatisticalmethodforevaluatin1902", //
-    bibkey = "journals/kansas/SokalM1902")
+    bibkey = "journals/kansas/SokalM1958")
 @Alias({ "upgma", "average", "average-link", "average-linkage", "UPGMA" })
 @Priority(Priority.RECOMMENDED + 1)
 public class GroupAverageLinkage implements Linkage {
diff --git a/elki-clustering/src/main/java/elki/clustering/hierarchical/linkage/WeightedAverageLinkage.java b/elki-clustering/src/main/java/elki/clustering/hierarchical/linkage/WeightedAverageLinkage.java
index 6b4d01d753..9f59bb9ca5 100644
--- a/elki-clustering/src/main/java/elki/clustering/hierarchical/linkage/WeightedAverageLinkage.java
+++ b/elki-clustering/src/main/java/elki/clustering/hierarchical/linkage/WeightedAverageLinkage.java
@@ -56,7 +56,7 @@
     title = "A statistical method for evaluating systematic relationship", //
     booktitle = "University of Kansas science bulletin 28", //
     url = "https://archive.org/details/cbarchive_33927_astatisticalmethodforevaluatin1902", //
-    bibkey = "journals/kansas/SokalM1902")
+    bibkey = "journals/kansas/SokalM1958")
 @Alias({ "wpgma", "WPGMA" })
 @Priority(Priority.DEFAULT - 1)
 public class WeightedAverageLinkage implements Linkage {