Paperbacks are available literally EVERYWHERE worldwide. For your convenience, I’ve included links to Amazon and Barnes and Noble below.
Bookshop.org is a wonderful organization that SUPPORTS LOCAL BOOKSTORES. It’s the same printer as Amazon and B&N and it’s discounted pricing. Consider checking them out and ordering your paperbacks from there (see link below).
However, you can request the paperbacks at any library or retailer listed at the bottom of this page.