At the moment only the Spanish version is available, but I am already working on the English translation.
After much effort, and thanks to the collaboration, among others, of Jose Rodriguez “Boriel” and Juan Antonio Rubio Garcia, my first commercial book is now a reality. You can buy it on Amazon in electronic version, soft cover or hard cover: https://www.amazon.es/Boriel-Basic-para-ZX-Spectrum/dp/B0CQD65FXZ
This book is a practical manual of “Boriel Basic”, which is a Sinclair Basic compiler, but with important improvements that allow you to program, if you want, with modern syntax.
It also includes libraries that allow you to manage sprites, scroll, compress data and break the limitations of traditional Basic.
My patrons can enjoy the digital version in PDF and EPUB for free.