You can use:
<xsl:for-each select="shf:BookShelf/shf:Book">
<tr>
<td><xsl:value-of select="bk:Name"/></td>
</tr>
</xsl:for-each>
And declare the namespaces in your <xsl:stylesheet>
:
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0"
xmlns:shf="BookShelf" xmlns:bk="BookType" xmlns:cmn="CommonType"> ...