Profession knowledge

Where else do i get these. So far I've gotten them from 3 weekly quests. Crafting orders, crafting 6 hammers( I'm blacksmithng) and going to cobalt assembly to gather weapons. There is also one from inscription. I've gotten one from a mythic plus, mining a node, opening a dragonscale treasure and killing an elite at the cobalt assembly. Is it just random? After the weekly quests and the inscription? Am I missing anymore that I can get? How many can I get per week?