Scopus search: TITLE-ABS-KEY
<p>I realized something strange when searching on Scopus' database.</p>

<p>If I query some words in the field "TITLE-ABS-KEY", I do not get the same  results as if I query each field individually, separated by "OR"s.</p>

<p>For example, the query:</p>

<blockquote>
  <p>TITLE-ABS-KEY ( flood  mitigation  dam  river  OR  stream )</p>
</blockquote>

<p>finds <strong>163</strong> papers.</p>

<p>Whereas the query:</p>

<blockquote>
  <p>TITLE ( flood  mitigation  dam  river  OR  stream )<br>
  OR  ABS ( flood  mitigation  dam  river  OR  stream )<br>
  OR  KEY ( flood  mitigation  dam
  river  OR  stream )</p>
</blockquote>

<p>finds only <strong>140</strong> papers.</p>

<p>Does anyone know if this is to be expected, and if so, what is the difference between both queries?</p>