Link to a sub-category

I want to link to a second level category from a Joomla article.  The only I can figure out how to do it now is to link to external URL instead of an internal link.  My page is  galiziengermandescendants.org/cms/en/doc...mns/all-family-books .
Joomla will allow linking to document-catcolumns, but I cannot find out how to link to the top level category.
Any ideas?
John

So basically, you want to show documents from top level category ? Why don't you create a menu item to link to Category menu item type directly ?

Tuan