<ref xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:mml="http://www.w3.org/1998/Math/MathML" id="R9"><label>9</label><element-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Hammer</surname><given-names>KA</given-names></name><name><surname>Carson</surname><given-names>CF</given-names></name><name><surname>Riley</surname><given-names>TV</given-names></name></person-group><article-title>Antimicrobial activity of essential oils and other plant extracts</article-title><source>Journal of Applied Microbiology</source><year>1999</year><volume>86</volume><issue>6</issue><fpage>985</fpage><lpage>990</lpage><pub-id pub-id-type="pmid">10438227</pub-id></element-citation></ref>