Nobody reads books, and for libs that do read books, they're just gonna read the new Obama book or something. You're asking someone to invest a lot of time reading when IMO the better thing to do is give them little snippets and ease them into it.

If you're gonna push something, please make a it a very short video or a podcast. And please be sure to gauge where they are. What I mean is that you don't want to be sending videos titled "how socialists need to organize in this day and age" or "why marxism-leninism is better than trotskyism" or whatever. You gotta understand, these libs think "socialism = red fash." So gauge the video/podcast and make sure it doesn't explicitly mention certain trigger words like "socialism" or "communism." A perfect example of something that doesn't, as many have said before, is Citations Needed. Even then, asking someone to listen to a 40+ min podcast is also a lot. Personally, for libs, I think short and to the point Majority Report clips are good. And if they want more, they can go from there.

Remember, we're still living in a world where entertainment value is something that you gotta consider, so if it can relate to pop-culture and subtly tie in leftist ideas without explicitly saying it, the better (Here's a good example relating to Star Wars and how droids are treated: https://www.youtube.com/watch?v=WD2UrB7zepo). You want them to come to realizations, not preach to them. When they want to find out more, they'll do it on their own or come to you for more recommendations.

This is something that I think the left needs to work on, i.e. some kind of "chart" that you can place different youtubers/podcasts on. This can be used as a reference after you've properly gauged where your lib friend/family/acquaintance is. For ex, if your friend is anti-police brutality but still thinks it's "bad apples," and they're kinda bro-ey, maybe a V*ush vid is good. If they're already on board with Sam Seder, then maybe push Michael Brooks (RIP).

Anyways, TL;DR please don't recommend books (b/c nobody reads), recommend short vids or podcasts and gauge where the person is before sending them some "death to landlords" shit.