diff --git a/en_US/howto/sogo.free.busy.md b/en_US/howto/sogo.free.busy.md
new file mode 100644
index 00000000..1866c865
--- /dev/null
+++ b/en_US/howto/sogo.free.busy.md
@@ -0,0 +1,16 @@
+# SOGo: free/busy availability
+
+If you want to let others to check your free/busy availability while inviting
+you to attend some calendar event, you need to grant one permission of your
+calendar to others.
+
+Let's use calendar `Personal Calendar` for example, you need to grant
+`View the Date & Time` permission for your public calendar events.
+
+![](./images/sogo/free.busy/grant.permission.png){: width=800px }
+
+After granted the permission, when other user (hosted on same server) is
+creating calendar event and input your email address as attendee, he can see
+your free/busy availability like this:
+
+![](./images/sogo/free.busy/check.availability.png){: width=800px }
diff --git a/en_US/howto/sogo.manage.resources.md b/en_US/howto/sogo.manage.resources.md
index c5013f37..974e2773 100644
--- a/en_US/howto/sogo.manage.resources.md
+++ b/en_US/howto/sogo.manage.resources.md
@@ -1,10 +1,16 @@
-# SOGo: Manage resources (Free/Busy)
+# SOGo: Manage resources
 
 [TOC]
 
 > This tutorial is a slight rewritten of SOGo wiki tutorial for iRedMail:
 > [Use Resources with SOGo](http://wiki.sogo.nu/ResourceConfiguration).
 
+!!! warning
+
+    This tutorial is for managing "Resources", if you just want to check the
+    attendee's (free/busy) availability while creating calendar event and inviting user,
+    please check this tutorial instead: 
+
 SOGo supports the management of resources like meeting rooms. A resource has,
 just like a person, a calendar, an email address and may be invited to events.
 The big difference is that resources auto accept invitations.
diff --git a/html/images/sogo/free.busy/check.availability.png b/html/images/sogo/free.busy/check.availability.png
new file mode 100644
index 00000000..0dfb7426
Binary files /dev/null and b/html/images/sogo/free.busy/check.availability.png differ
diff --git a/html/images/sogo/free.busy/grant.permission.png b/html/images/sogo/free.busy/grant.permission.png
new file mode 100644
index 00000000..4053fbeb
Binary files /dev/null and b/html/images/sogo/free.busy/grant.permission.png differ
diff --git a/html/index.html b/html/index.html
index 900b56e9..275d992b 100644
--- a/html/index.html
+++ b/html/index.html
@@ -142,7 +142,8 @@
 <li><a href="restrict.mail.user.to.login.from.specified.ip.or.networks.html">Restrict mail user to login from specified IP addresses or networks</a></li>
 <li><a href="send.out.email.from.specified.ip.addresses.html">Send out email from specified IP address</a></li>
 <li><a href="sign.disclaimer.html">Sign disclaimer on outgoing mails</a></li>
-<li><a href="sogo.manage.resources.html">SOGo: Manage resources (Free/Busy)</a></li>
+<li><a href="sogo.free.busy.html">SOGo: free/busy availability</a></li>
+<li><a href="sogo.manage.resources.html">SOGo: Manage resources</a></li>
 <li><a href="sql.add.alias.domain.html">SQL: Add an alias domain</a></li>
 <li><a href="sql.create.catch-all.html">SQL: Add per-domain catch-all account</a></li>
 <li><a href="sql.create.mail.alias.html">SQL: Add a mail alias account</a></li>
diff --git a/html/sogo.free.busy.html b/html/sogo.free.busy.html
new file mode 100644
index 00000000..7b3a934a
--- /dev/null
+++ b/html/sogo.free.busy.html
@@ -0,0 +1,40 @@
+<!DOCTYPE html>
+<html>
+    <head>
+        <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
+        <title>SOGo: free/busy availability</title>
+        <link rel="stylesheet" type="text/css" href="./css/markdown.css" />
+    </head>
+    <body>
+
+    <div id="navigation">
+    <a href="https://www.iredmail.org" target="_blank">
+        <img alt="iRedMail web site"
+             src="./images/logo-iredmail.png"
+             style="vertical-align: middle; height: 30px;"
+             />&nbsp;
+        <span>iRedMail</span>
+    </a>
+    &nbsp;&nbsp;//&nbsp;&nbsp;<a href="./index.html">Document Index</a></div><h1 id="sogo-freebusy-availability">SOGo: free/busy availability</h1>
+<p>If you want to let others to check your free/busy availability while inviting
+you to attend some calendar event, you need to grant one permission of your
+calendar to others.</p>
+<p>Let's use calendar <code>Personal Calendar</code> for example, you need to grant
+<code>View the Date &amp; Time</code> permission for your public calendar events.</p>
+<p><img alt="" src="./images/sogo/free.busy/grant.permission.png" width="800px" /></p>
+<p>After granted the permission, when other user (hosted on same server) is
+creating calendar event and input your email address as attendee, he can see
+your free/busy availability like this:</p>
+<p><img alt="" src="./images/sogo/free.busy/check.availability.png" width="800px" /></p><div class="footer">
+    <p style="text-align: center; color: grey;">All documents are available in <a href="https://github.com/iredmail/docs/">BitBucket repository</a>, and published under <a href="http://creativecommons.org/licenses/by-nd/3.0/us/" target="_blank">Creative Commons</a> license. You can <a href="https://github.com/iredmail/docs/archive/master.zip">download the latest version</a> for offline reading. If you found something wrong, please do <a href="https://www.iredmail.org/contact.html">contact us</a> to fix it.</p>
+</div>
+<!-- Global site tag (gtag.js) - Google Analytics -->
+<script async src="https://www.googletagmanager.com/gtag/js?id=UA-3293801-21"></script>
+<script>
+  window.dataLayer = window.dataLayer || [];
+  function gtag(){dataLayer.push(arguments);}
+  gtag('js', new Date());
+
+  gtag('config', 'UA-3293801-21');
+</script>
+</body></html>
\ No newline at end of file
diff --git a/html/sogo.manage.resources.html b/html/sogo.manage.resources.html
index 85fc0cc9..37ba436c 100644
--- a/html/sogo.manage.resources.html
+++ b/html/sogo.manage.resources.html
@@ -2,7 +2,7 @@
 <html>
     <head>
         <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
-        <title>SOGo: Manage resources (Free/Busy)</title>
+        <title>SOGo: Manage resources</title>
         <link rel="stylesheet" type="text/css" href="./css/markdown.css" />
     </head>
     <body>
@@ -15,10 +15,10 @@
              />&nbsp;
         <span>iRedMail</span>
     </a>
-    &nbsp;&nbsp;//&nbsp;&nbsp;<a href="./index.html">Document Index</a></div><h1 id="sogo-manage-resources-freebusy">SOGo: Manage resources (Free/Busy)</h1>
+    &nbsp;&nbsp;//&nbsp;&nbsp;<a href="./index.html">Document Index</a></div><h1 id="sogo-manage-resources">SOGo: Manage resources</h1>
 <div class="toc">
 <ul>
-<li><a href="#sogo-manage-resources-freebusy">SOGo: Manage resources (Free/Busy)</a><ul>
+<li><a href="#sogo-manage-resources">SOGo: Manage resources</a><ul>
 <li><a href="#requirements">Requirements</a></li>
 <li><a href="#openldap-backend">OpenLDAP backend</a><ul>
 <li><a href="#add-missing-ldap-schema-files">Add missing LDAP schema files</a></li>
@@ -35,6 +35,12 @@
 <p>This tutorial is a slight rewritten of SOGo wiki tutorial for iRedMail:
 <a href="http://wiki.sogo.nu/ResourceConfiguration">Use Resources with SOGo</a>.</p>
 </blockquote>
+<div class="admonition warning">
+<p class="admonition-title">Warning</p>
+<p>This tutorial is for managing "Resources", if you just want to check the
+attendee's (free/busy) availability while creating calendar event and inviting user,
+please check this tutorial instead: </p>
+</div>
 <p>SOGo supports the management of resources like meeting rooms. A resource has,
 just like a person, a calendar, an email address and may be invited to events.
 The big difference is that resources auto accept invitations.</p>
