"Hammersmith Subway" (Map). Google Maps. The north of the two roundels is the Hammersmith & City and Circle lines station, the south one is the Piccadilly and District lines station.
Hardy, Brian, ed. (March 2011). "How it used to be – freight on The Underground 50 years ago". Underground News (591). London Underground Railway Society: 175–183. ISSN0306-8617.