Interested in the history of the vacuum tube?

The genesis of the vacuum tube is shown in this 11 minute film called Bottle of Magic.
They mention something called the 6AK7 used in the military, and what look like early 300Bs are shown.
[]Above link
Would like to add this one as well.

Electrons on Parade part 1.

Electrons on Parade part 2.
Google: Joes tube lore
Also, on Anthem/sonic frontiers site search for "a taste of tubes