def METHOD_NAME(self):
    self.maxDiff = None
    xml = (
        """
        <article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" article-type="research-article" dtd-version="1.1" specific-use="sps-1.9" xml:lang="en">
        <back>
        <ref-list>
        <title>REFERENCES</title>
        <ref id="B1">
        <label>1.</label>
        <mixed-citation>
        1. Tran B, Falster MO, Douglas K, Blyth F, Jorm LR. Smoking and potentially preventable hospitalisation: the benefit of smoking cessation in older ages. Drug Alcohol Depend. 2015;150:85-91. DOI: <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1016/j.drugalcdep.2015.02.028">https://doi.org/10.1016/j.drugalcdep.2015.02.028</ext-link>
        </mixed-citation>
        <element-citation publication-type="journal">
        <person-group person-group-type="author">
        <name>
        <surname>Tran</surname>
        <given-names>B</given-names>
        <prefix>The Honorable</prefix>
        <suffix>III</suffix>
        </name>
        <name>
        <surname>Falster</surname>
        <given-names>MO</given-names>
        </name>
        <name>
        <surname>Douglas</surname>
        <given-names>K</given-names>
        </name>
        <name>
        <surname>Blyth</surname>
        <given-names>F</given-names>
        </name>
        <name>
        <surname>Jorm</surname>
        <given-names>LR</given-names>
        </name>
        </person-group>
        <article-title>Smoking and potentially preventable hospitalisation: the benefit of smoking cessation in older ages</article-title>
        <source>Drug Alcohol Depend.</source>
        <year>2015</year>
        <volume>150</volume>
        <fpage>85</fpage>
        <lpage>91</lpage>
        <pub-id pub-id-type="pmid">00000000</pub-id>
        <pub-id pub-id-type="pmcid">11111111</pub-id>
        <comment>
        DOI:
        <ext-link ext-link-type="uri" xlink:href="https://doi.org/10.1016/j.drugalcdep.2015.02.028">https://doi.org/10.1016/j.drugalcdep.2015.02.028</ext-link>
        </comment>
        </element-citation>
        </ref>
        <ref id="B2">
            <mixed-citation>BARTHES, Roland. <italic>Aula</italic>. São Pulo: Cultrix, 1987.</mixed-citation>
            <element-citation publication-type="book">
              <person-group person-group-type="author">
                <name>
                  <surname>BARTHES</surname>
                  <given-names>Roland</given-names>
                </name>
              </person-group>
              <source>Aula</source>
              <publisher-loc>São Pulo</publisher-loc>
              <publisher-name>Cultrix</publisher-name>
              <year>1987</year>
              <pub-id pub-id-type="pmid">22222222</pub-id>
              <pub-id pub-id-type="pmcid">33333333</pub-id>
            </element-citation>
          </ref>
        </ref-list>
        </back>
        </article>
        """
    )
    xmltree = etree.fromstring(xml)
    self.citations = ArticleCitations(xmltree)