<series xlink:type="extended" xmlns:xlink="http://www.w3.org/1999/xlink">  <author>L. Frank Baum</author>  <!-- locator elements -->  <novel xlink:type="locator" xlink:label="oz1"         xlink:href="ftp://archive.org/pub/etext/etext93/wizoz10.txt">    <title>The Wonderful Wizard of Oz</title>    <year>1900</year>  </novel>  <novel xlink:type="locator" xlink:label="oz2"         xlink:href="ftp://archive.org/pub/etext/etext93/ozland10.txt">    <title>The Marvelous Land of Oz</title>    <year>1904</year>  </novel>  <novel xlink:type="locator" xlink:label="oz3"         xlink:href="ftp://archive.org/pub/etext/etext93/wizoz10.txt">    <title>Ozma of Oz</title>    <year>1907</year>  </novel>  <!-- arcs -->  <next     xlink:type="arc" xlink:from="oz1" xlink:to="oz2" />  <next     xlink:type="arc" xlink:from="oz2" xlink:to="oz3" />  <previous xlink:type="arc" xlink:from="oz2" xlink:to="oz1" />  <previous xlink:type="arc" xlink:from="oz3" xlink:to="oz2" /></series>