diff --git a/HOWTO.md b/HOWTO.md
index 04ed802..33d8f56 100644
--- a/HOWTO.md
+++ b/HOWTO.md
@@ -1,12 +1,38 @@
+<!--
+{% comment %}
+Licensed to Julian Hyde under one or more contributor license
+agreements.  See the NOTICE file distributed with this work
+for additional information regarding copyright ownership.
+Julian Hyde licenses this file to you under the Apache
+License, Version 2.0 (the "License"); you may not use this
+file except in compliance with the License.  You may obtain a
+copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing,
+software distributed under the License is distributed on an
+"AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
+either express or implied.  See the License for the specific
+language governing permissions and limitations under the
+License.
+{% endcomment %}
+-->
+
 # Quidem HOWTO
 
 Here's some miscellaneous documentation about using and developing Quidem.
 
 # Release
 
-Make sure that `./mvnw clean install site` runs on JDK 8, 11 and 17
+Make sure that `./mvnw clean install site` runs on JDK 11, 17 and 21
 on Linux, macOS and Windows.
-Also check [Travis CI](https://travis-ci.org/julianhyde/quidem).
+
+Upgrade dependencies to their latest release: run
+```bash
+./mvnw versions:update-properties
+```
+and commit the modified `pom.xml`.
 
 Update the [release history](HISTORY.md),
 the version number at the bottom of [README](README.md),
diff --git a/NOTICE b/NOTICE
index 5aa3b14..afa82c4 100644
--- a/NOTICE
+++ b/NOTICE
@@ -1,6 +1,6 @@
 Quidem
 Idempotent query executor
-Copyright (C) 2014-2022 Julian Hyde
+Copyright (C) 2014-2023 Julian Hyde
 
 ===============================================================================
 Licensed under the Apache License, Version 2.0 (the "License");
diff --git a/pom.xml b/pom.xml
index fa486e7..332a765 100644
--- a/pom.xml
+++ b/pom.xml
@@ -58,24 +58,24 @@
     <top.dir>${project.basedir}</top.dir>
 
     <!-- Component and plugin versions, in alphabetical order. -->
-    <build-helper-maven-plugin.version>3.3.0</build-helper-maven-plugin.version>
-    <checkerframework.version>3.24.0</checkerframework.version>
+    <build-helper-maven-plugin.version>3.5.0</build-helper-maven-plugin.version>
+    <checkerframework.version>3.42.0</checkerframework.version>
     <!-- We support checkstyle 9.3 and higher; 10.0 requires JDK 11 or higher. -->
-    <checkstyle.version>10.4</checkstyle.version>
+    <checkstyle.version>10.12.7</checkstyle.version>
     <git-commit-id-plugin.version>4.9.10</git-commit-id-plugin.version>
     <!-- We support Guava versions 19.0 and higher. -->
-    <guava.version>31.1-jre</guava.version>
+    <guava.version>33.0.0-jre</guava.version>
     <hamcrest.version>2.2</hamcrest.version>
-    <hsqldb.version>2.7.1</hsqldb.version>
-    <junit-jupiter.version>5.9.1</junit-jupiter.version>
-    <maven-checkstyle-plugin.version>3.2.0</maven-checkstyle-plugin.version>
-    <maven-compiler-plugin.version>3.10.1</maven-compiler-plugin.version>
-    <maven-enforcer-plugin.version>3.1.0</maven-enforcer-plugin.version>
-    <maven-gpg-plugin.version>3.0.1</maven-gpg-plugin.version>
-    <maven-javadoc-plugin.version>3.4.1</maven-javadoc-plugin.version>
-    <maven-site-plugin.version>3.12.1</maven-site-plugin.version>
-    <maven-source-plugin.version>3.2.1</maven-source-plugin.version>
-    <maven-surefire-plugin.version>3.0.0-M7</maven-surefire-plugin.version>
+    <hsqldb.version>2.7.2</hsqldb.version>
+    <junit-jupiter.version>5.10.1</junit-jupiter.version>
+    <maven-checkstyle-plugin.version>3.3.1</maven-checkstyle-plugin.version>
+    <maven-compiler-plugin.version>3.12.1</maven-compiler-plugin.version>
+    <maven-enforcer-plugin.version>3.4.1</maven-enforcer-plugin.version>
+    <maven-gpg-plugin.version>3.1.0</maven-gpg-plugin.version>
+    <maven-javadoc-plugin.version>3.6.3</maven-javadoc-plugin.version>
+    <maven-site-plugin.version>4.0.0-M13</maven-site-plugin.version>
+    <maven-source-plugin.version>3.3.0</maven-source-plugin.version>
+    <maven-surefire-plugin.version>3.2.5</maven-surefire-plugin.version>
     <scott-data-hsqldb.version>0.2</scott-data-hsqldb.version>
 
     <maven-javadoc-plugin.additionalOptions>-html5</maven-javadoc-plugin.additionalOptions>