The book you linked in the question (http://deconcentration-of-attention.com/psychonetics.html) is the most comprehensive resource in English I've seen. It also covers basic exercises really well, I can help you with translating more advanced ones once you hit the ceiling.
I studied it with Oleg Bakhtiyarov over a decade ago, AMA. In short, it's a corpus of techniques that use attention control beyond mere focus as the main tool. Some borrowed, some novel, but all neatly organised into a framework that allows you to do mind state "algebra" first and then try to reach these new states you derived. Techniques are working, helped me both in maintaining cognitive flexibility and creativity over time and to handle a few extreme situations in my life. There is lot of mythology around outstanding results achieved using these techniques but neither Oleg nor other experienced psychonetics practitioners never demonstrated them to us, only relayed anecdotes.
1There is also some attempt to generalise and further develop Ostrom's ideas: https://www.prosocial.world
To name a few: