It seems almost every prison has it own rules regarding books,and magazines. One P/P i have in Mininsota syas that it is possible to send these directly.

" The only thing besides letters pictures and photos that can be mailed is books.Up to 5 books can be mailed direct But you must write X ( being the number of books you have enclosed) book/s enclosed per B.O.P policy on the package."

Whereas most Prisons insist that the books come straight from the publisher or store ( such as Amazon)

I think it's best that you check first with th the particular Prison what the regulations are