Service activities and/or establishments which directly serve the needs of the permitted uses in § 143-116A and B herein, including but not limited to such uses as pharmacy, optometrist, dental equipment laboratory, employee cafeteria or snack bar, conference rooms or union hall, including ancillary kitchen facilities, copy center and any other use of a similar nature; provided, however, that any such use shall be ancillary to the primary use of the district, intended to provide services to the permitted uses and not intended to serve the general public. No external signs advertising said use(s) shall be permitted.