Usefull websites and tools:
Manufacturing Calculators:
EVE Isk per Hour: https://eveiph.github.io/
Not completely up to date on mechanics (lacks support for Citadels), but reasonably close in most cases. Allows rather complex calculations for lots of items at the same time. Also comes with a simple Blueprint Manager.
Steve Ronukens Toolbox: https://www.fuzzwork.co.uk/
Offers various tools usefull for an industrialist. Very good for quickly looking up things, but lacks the ability to manage a more complex operation.
EVE Industry: https://eve-industry.org/calc/
very minimalistic tool for simple lookups. Fast and easy to use
EVE-Cost: http://www.eve-cost.eu/
Allows management of more complex operations.
Blogs:
Youtube/Twitch
MindFluff: https://www.youtube.com/channel/UCcDVu3mIiW37rix7V1g_RQg
Has a bunch of videos about industry and trading.
CCP Flight Academy: https://www.youtube.com/playlist?list=PLuyyCPSovFqgbqZ4-oq0fgeI9QcdH78lr
They have few videos related to industry, but they are only usefull for absolute newbies.
Websites and other Ressources
The UniWiki from Eve University: https://wiki.eveuniversity.org/Main_Page
Fantastic collection of in-detail explanations of gamemechanic. Sometimes a bit overloaded and out of date, but usually a really good place to look for information.