s it possible to learn by retreats?
Does there excist books where the systems explained further?
Or is it only to learn by becoming geshe?
Tashi delek Bönkyab,
Sorry for my very late reply, but you would certainly know why this reply would be so late .....
We can see Bön as:
If you are a starter you should practice and study first Sutra.
Then Tantra maybe and continue with Dzogchen, the crown on the 9 ways of Bön.
Further you realy have to practice the Ngöndro or preliminaries.
One never can built a castle on sand.
So a good foundation of concrete and steel that is for you , i guess a good case.
To become a Geshe that is for the most of westerns not possible.
But as a layman etc. one can sure become enlightened.