if ( open( FH, <data.sgl")
{
    local $/ = "</ref>\n"; # make close-tag the input rec. separator

    while (<FH>)   # now read a full "ref" element into $_
    {
        next unless ( m{<aulist>.*?$search.*?</aulist>}is );
        # now split the ref element up and print it
        # <strike>(I'll leave that as an exercise...)</strike>

        # Since you have a finite number of things you want
        # to put into your output listing, it'll be easiest
        # just to look for those things:

        for my $fld ( qw/author year source keys title/ ) {
           @{$data{$fld}} = m{<$fld>([^<]+)}ig;
        }
        print_record( \%data ); # all hash elements are array refs
             # (some may be empty/undef, some may have 1 item)
    }
    close FH;
}
else 
{
    die "Unable to read data.sgl\n";
}