namespace problem

hello,everyone,who can explain this problem to me:
I got an xml file with namspace

<?xml version="1.0" encoding="gb2312"?>
<?xml-stylesheet type="text/xsl" href="sortsample.xsl"?>
<a:bookinfo xmlns:a="http://www.example.com/catalog/">
<a:books>
	<a:book>
		<a:ISBN>069-1300886</a:ISBN>
		<a:Name>¼òÃ÷ÎÄ»¯³£Ê¶</a:Name>
		<a:Press>Î人³ö°æÉç</a:Press>
		<a:Price>10.50</a:Price>
		<a:PublishDate>1999-10-01</a:PublishDate>
		<a:Author>Defi.W</a:Author>
		<a:Author>ÕÅ·É</a:Author>
		<a:Qty>1000</a:Qty>
	</a:book>
</a:books>	
</a:bookinfo>

then how should i write proper XSLT file to retrieve information from this document?

Addtion:
if i use defaul namespace as xmlns="http://www.example.com/catalog/>",
how should i do same thing as above?

Thanks




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