Hi Cheryl,
Welcome to SalonGeek.
Books are fine for all the theory and you could try borrowing them from the library first to see if you find them readable.
I’d probably look at getting a level 3 text book as it refreshes level 2 basics and goes into more depth in other areas plus a book dedicated to colour theory.
Hairdressing is skills based and a lot of cutting technique videos on YouTube are awful in my opinion, because they’re just chopping away in a haphazard fashion but you’ll see lots of positive comments from people who don’t seem to know any better.
I do recommend
www.freesaloneducation.com for really good cutting and colour videos that teach good techniques. You’ll probably find them more helpful after you’ve gained a basic understanding of cutting theory, before diving in.
Having a good technique is the difference between a mediocre hair cut and an outstanding haircut, and the cut will hold its shape for a few weeks longer, if it’s done well in the first place.
I’d also strongly recommend a subscription to :
https://myhairdressers.com/
I haven’t used them for a while but they used to include an awful lot of extremely well written theory notes within the subscription that you can copy and print off and put into a ring binder. You probably wouldn’t need to buy any textbooks in that case. They used to offer a free trial period so check to see what options are available. They also regularly offer half price deals on the annual subscription rate, so get yourself on their mailing list.
Hope this is useful information for now?