#! /usr/bin/perl -w

use strict;

my @sortable;
while ( <DATA> ) {

    # are we in the ref's?
    if (/^\<ref/)
    {
        # keep track of it, but don't print it out yet.
        push @sortable, $_;
        next;
    }
    
    # else, are we done ref's?
    if (@sortable)
    {
        print for sort @sortable;
        # done with them, get rid of 'em.
        @sortable = ();
    }

    # this line can be printed out at this point.
    print;
}


__DATA__
[ same as yours, so I'm not repeating it ]