Monopolies and Restrictive Practices Commission (1951). Report on the Supply of Electric Lamps(PDF). London: His Majesty's Stationery Office. p. 98. ISBN010518487X. Archived(PDF) from the original on 5 September 2019. Retrieved 14 April 2020.
Monopolies and Restrictive Practices Commission (1951). Report on the Supply of Electric Lamps(PDF). London: His Majesty's Stationery Office. p. 98. ISBN010518487X. Archived(PDF) from the original on 5 September 2019. Retrieved 14 April 2020.