<xsl:for-each select="instruments/instrument">
<xsl:variable name="descr" select="description[@lang='de']"/>
<xsl:value-of select="$descr" />
</xsl:for-each>
<xsl:for-each select="instruments/instrument">
<xsl:variable name="descr" select="description[@lang='de']"/>
<xsl:value-of select="$descr" />
</xsl:for-each>