*DDI-1 Disc Drive and Interface User manual © Copyright Amstrad plc
*GX4000 User Instructions © Copyright Amstrad plc
* '''[nocash]''' [[Dk'tronics memory expansion|Dk'Tronics 64k RAM Expansion ]] manual [[Media:Dkt64k.pdf|pdf]]
*The Amstrad CPC Firmware Guide by Bob Taylor and Thomas Defoe
*DES Programming Manual by Michael Beckett and Capursoft