I mention this book a lot, but it's good.

https://www.amazon.co.uk/BAMN-Any-Means-Necessary-Manifestos...

https://www.goodreads.com/book/show/987215.BAMN

You only have to look at some of the ephemera to see that there was plenty of violent ideology around, eg SCUM (Society for Cutting Up Men - 1967 https://en.wikipedia.org/wiki/SCUM_Manifesto ).

If you're interested you might like BAMN - Outlaw Manifestos and Ephemera 1965-1970 https://www.amazon.co.uk/BAMN-Any-Means-Necessary-Manifestos...

If you're interested in the counter-culture of the 1960s the book BAMN (By Any Means Necessary): Outlaw Manifestos and Ephemera, 1965-70 is interesting.

https://www.amazon.co.uk/BAMN-Any-Means-Necessary-Manifestos...

https://www.goodreads.com/book/show/987215.BAMN

https://books.google.co.uk/books/about/BAMN_By_Any_Means_Nec...

People may also be interested in "BAMN - Outlaw Manifestos and Ephemera 1965-1970"

http://www.amazon.co.uk/BAMN-Any-Means-Necessary-Manifestos/...