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The vast majority of historical anarchist and Marxist theory was spread among workers by short articles in papers and pamphlets, rather than big books. Social movements always tried to make ideas accessible and in the modern world there is now leftist YouTube and podcasts.
To learn about Marxism watch @RPlateaus https://www.youtube.com/c/RedPlateaus
For historical anarchist theory see my videos https://www.youtube.com/c/anarchopac
Anark has good videos on strategy which incorporate modern theory, including black anarchism https://www.youtube.com/c/Anark
For great documentaries on contemporary social movements and current events watch sub media. https://sub.media/
For concrete advice on organising listen to @RebelSteps. Its especially good for featuring people with on the ground experience. https://rebelsteps.com/
Several different anarchist podcasts can be found on the channel zero network https://channelzeronetwork.com/
For interesting discussions on leftist books I highly recommend @abcdannyandjim. They also have a number of great interviews with anarchist historians. https://anchor.fm/abcwithdannyandjim
