For Coaches at Practice:

https://www.adidas.com/us/blog/878508-5-soccer-goalie-drills-for-a-complete-practice

https://blayze.io/blog/soccer/6-drills-for-goal-keepers-to-block-any-shot

For individual Practice:

https://www.just-keepers.com/blog/practising-alone-goalkeeping-drills-you-can-try-on-your-own/

Book Recommendations:

* So you want to be a Goalkeeper (Joe Machnik & Paul Harris)

* So now you are a Goalkeeper (Joe Machnik & Frans Hoek)

Unfortunately both these books are out of print but they can be found at used books sites, they're not cheap but they're great resources. I with have some recommendations that are in print soon!