sub InitEanFromBiblionumber{
    my $biblionumber = shift;
    my $ean;
    my $record = GetMarcBiblio($biblionumber);
    if ( !$record ) {return '0';}
    my $ean_10a;
    if ( C4::Context->preference("marcflavour") eq "UNIMARC" ) {
        if ( !$record->field('010')) {return '0';}
        if ( !$record->field('010')->subfield("a")) {return '0';}
        $ean_10a=$record->field('010')->subfield("a");
    }
    else{
        if ( !$record->field('020')) {return '0';}
        if ( !$record->field('020')->subfield("a") ) {return '0';}
        $ean_10a=$record->field('020')->subfield("a");
    }
    $ean_10a=~s/\D//g;
    #warn Data::Dumper::Dumper $ean_10a;
    if($ean_10a=~m/^[\d]{13}$/){
        $ean=$ean_10a;
    }
    elsif(($ean_10a=~m/^[\d]{10}$/) or ($ean_10a=~m/^[\d]{9}$/)){
        my $eancalc="978".$ean_10a;
        my @eant=split('',$eancalc);
        my $c13 = ((10-(($eant[0]+3*$eant[1]+$eant[2]+3*$eant[3]+$eant[4]+3*$eant[5]+$eant[6]+3*$eant[7]+$eant[8]+3*$eant[9]+$eant[10]+3*$eant[11])%10))%10);
        $ean=substr($eancalc,0,12) .$c13;
        #warn Data::Dumper::Dumper $c13;
    }
    else{
        return '0';
    }
    #warn Data::Dumper::Dumper $ean;
    return $ean;
}