[Koha] How to make researchable only records with phisical items?

[jops]

Hi everyone,
 I'm a koha newbie and this is my installation
http://koha.magma.im
I have imported some marc records but I would like to set researchable
only the records that have at least one item.
For example I'd like to search only records like this
http://koha.magma.im/cgi-bin/koha/opac-detail.pl?biblionumber=4807
and not these ones with no phisical items
http://koha.magma.im/cgi-bin/koha/opac-detail.pl?biblionumber=4638

How to do it?

Thanks in advance


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jops

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