* [https://sinclair.zilog.fr Sinclair's Spirit (FR)] Learn how to code with Z80 Assembler on ZX Spectrum with [[BDCIron]]
* [https://problemkaputt.de/zxdocs.htm Noca$h's ZXdocs]
* [httphttps://wwwworldofspectrum.retro8bitcomputers.co.uknet/Contentitem/downloads2000357/books/SpectrumHardwareManual_2ndEdition.pdf Spectrum Hardware Manual] [https://pdfcoffee.com/the-zx-spectrum-ula-how-to-design-a-micro-chris-smith-pdf-free.html The ZX Spectrum ULA ebook]
* [https://worldofspectrum.net/documentation/ World of Spectrum] [https://www.spectrumforeveryone.com/technical/ Spectrum for Everyone] [https://sinclair.wiki.zxnet.co.uk Sinclair Wiki] Documentation
* [https://worldofspectrum.net/pub/sinclair/ World of Spectrum file server]