DOCBOOK-APPS: alternate ulinks for print and html?

Is it possible to provide different URLs for ulinks depending on whether I am using a print or html stylesheet? I don't want to do this for all ulinks, just select ones. I am picturing something like:
<ulink url="printurl.com" type="print">Somewhere</ulink>
<ulink url="htmlurl.com" type="html">Somewhere Else</ulink>
where only one of these would generate a link, depending on the backend. Is there an existing attribute for differentiating print and html markup?

My application is that I would like to provide links to Amazon and B&N for books in the html version of my bibliography, but not in the print version. I want to make such a distincion only in the bibliography, i.e. I would like these particular ulinks to be active only in html.

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Kevin M. Dunn
Professor of Chemistry
Hampden-Sydney College
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