<element-citation publication-type="thesis"> should be converted to <unstructured_citation>

[Melissa37]

Our kitchen sink example:

<ref id="bib38">
        <element-citation publication-type="thesis">
            <person-group person-group-type="author">
                <name>
                    <surname>Schneider</surname><given-names>P</given-names>
                </name>
            </person-group>
            <year iso-8601-date="2006">2006</year>
            <article-title>PhD thesis: Submicroscopic <italic>Plasmodium falciparum</italic> gametocytaemia and the contribution to malaria transmission</article-title>
            <publisher-name>Radboud University Nijmegen Medical Centre</publisher-name>
            <publisher-loc>Nijmegen, The Netherlands</publisher-loc>
        </element-citation>
    </ref>

Crossref output:

<citation key="38">
                        <author>Schneider</author>
                        <cYear>2006</cYear>
                        <article_title>PhD thesis: Submicroscopic Plasmodium falciparum gametocytaemia and the contribution to malaria transmission</article_title>
                    </citation>

Suggested change to:

<unstructured_citation>Schneider P. 2006. PhD thesis: Submicroscopic Plasmodium falciparum gametocytaemia and the contribution to
malaria transmission. Nijmegen, The Netherlands: Radboud University Nijmegen Medical Centre.</unstructured_citation>