xpath lesson

thing.xml

<?xml version="1.0"?>
<bookstore specialty="novel">
  <book style="autobiography">
    <author>
      <first-name>Joe</first-name>
      <last-name>Bob</last-name>
      <award>Trenton Literary Review Honorable Mention</award>
    </author>
    <price>12</price>
  </book>
  <book style="textbook">
    <author>
      <first-name>Mary</first-name>
      <last-name>Bob</last-name>
      <publication>Selected Short Stories of
        <first-name>Mary</first-name>
        <last-name>Bob</last-name>
      </publication>
    </author>
    <editor>
      <first-name>Britney</first-name>
      <last-name>Bob</last-name>
    </editor>
    <price>55</price>
  </book>
  <magazine style="glossy" frequency="monthly">
    <price>2.50</price>
    <subscription price="24" per="year"/>
  </magazine>
  <book style="novel" id="myfave">
    <author>
      <first-name>Toni</first-name>
      <last-name>Bob</last-name>
      <degree from="Trenton U">B.A.</degree>
      <degree from="Harvard">Ph.D.</degree>
      <award>Pulitzer</award>
      <publication>Still in Trenton</publication>
      <publication>Trenton Forever</publication>
    </author>
    <price intl="Canada" exchange="0.7">6.50</price>
    <excerpt>
      <p>It was a dark and stormy night.</p>
      <p>But then all nights in Trenton seem dark and
      stormy to someone who has gone through what
      <emph>I</emph> have.</p>
      <definition-list>
        <term>Trenton</term>
        <definition>misery</definition>
      </definition-list>
    </excerpt>
  </book>
</bookstore>