It is a handbook for resistance against a dictatorship, pretty famous among resistance movements worldwide because it was built on actual extensive study of what does and doesn't work in a whole lot of worldwide situations both successful and not.

This talks more about it: https://en.wikipedia.org/wiki/From_Dictatorship_to_Democracy

It is also here: https://archive.org/details/from_dictatorship_to_democracy_1306_librivox