Citation Hunt

The Wikipedia snippet below is not backed by a reliable source. Can you find one?

Click I got this! to go to Wikipedia and fix the snippet, or Next! to see another one. Good luck!

In page Acorn Electron:

This text has been unreferenced on Wikipedia for a very long time. If you can't find a source, be bold and remove it!

"

Since the Electron provides only a selection of video output ports, a cassette port and the expansion connector, a range of additional expansions were produced to offer ports and connections to various peripherals. The first expansions were largely joystick and printer interfaces or sideways ROM boards.[1] For instance, First Byte Computers developed an interface and software which allowed a "switched" joystick to be used with the majority of software titles.[2] This interface became very popular and was sold by W.H. Smiths, Boots, Comet and hundreds of independent computer dealers,[citation needed] selling as many as 23,000 units over a two-year period, helped by a bundling agreement with Dixons.[3]