Importing issues to OJS (using XML Plugin) - where to place keywords and references?

I try to import old issues of my university journal to OJS, using XML plugin. I built xml issue files:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE issue PUBLIC "-//PKP//OJS Articles and Issues XML//EN" "http://ift.tt/175Gbz8">

<issue published="false" current="false">
<title>August 2008, Volume 3, Number A08</title>
<volume>3</volume>
<number>A08</number>
<year>2008</year>

<section>
<title locale="en_US">Articles</title>
<abbrev locale="en_US">ART</abbrev>


<article>
<title>Approximating Counterparts</title>
<abstract>Abstract text...</abstract>
<pages>1-11</pages>
<date_published>2008-08-01</date_published>
<author primary_contact="true">
<firstname>FISTNAME</firstname>
<middlename><![CDATA[ ]]></middlename>
<lastname>LASTNAME</lastname>
<email>email@email</email>
</author>
<galley>
<label>PDF</label>
<file><href mime_type="application/pdf" src="http://...../issue/some.pdf"/></file>
</galley>
</article>


</section>
</issue>

And successfully imported them to OJS. However, I have a problem with keywords and references. I don't know where to place them in my sample.xml file. Tags like <keywords>...</keywords> or <references>...</references> seem not to work, I mean they have no effect when I place them in my sample.xml file. Any ideas how to solve it?