sub ReadSource( $ $ )
{
    my $DataSource = shift;
    my $HashRef    = shift;
    
    foreach my $ItemID (@Data)
    {
        my $data_array_ref = $HashRef->{$ItemID};

        if ( $data_array_ref )
        {
            push( @{$data_array_ref}, $DataSource );
        }
        else
        {
            $HashRef->{$ItemID} = [ $DataSource ];
        }
    }
}