Well i was reading about the different genres of metal around their characteristics styles origins, and how they all differ or are similar to one another. This brought to my memory the documentary by that Canadian guy "Metal a Headbangers Journey" and got me thinking on what other documentaries and literature could have been created regarding metal from its genres to its origins and styles so i ask you all if you know of any good books or documentaries to share them here.
If you're interested, the same guy, Sam Dunn, made a series after his documentary in 2005 called Metal Evolution. He dedicates an episode to most major sub-genres and studies them culturally and musically. Most of the episodes you can find on YT and they're pretty indepth.