Hello,
I rather like the book by Myra Mahoney ~ "The Really Useful Guinea Pig Guide"

It's a good book to start up with.
All of the books by Peter Gurney contain an abundance of guinea care info and are worth looking at.
It's worth keeping in mind though that ideas change on the care of animals and nothing read in books should be taken as the final word on the subject
The internet is a good source of knowledge as are forums, but again, all guinea pig owners will have their own thoughts and ideas, so don't take anything as the "gospel." If you understand me.
The Cambridge Cavy Trust is a very reliable source of advice, you might want to consider becoming a member?
I'm not sure what you mean by guinea anal glands? Do you mean the scent glands in their anal sac? It can be all very confusing when you start out can't it

Good luck, I'm sure lot's of other members Will recommend books for you and well done on taking the time to learn about your pets.
Barbara