Interesting. This is a group of libraries that recognizes single works of art (drawn or written by words) on small books they send out. The artist/writer then does what they want to the book and fills it with his works. Each book is about 20 to 30 pages - about the size of an 8 1/2 X 11 folded in half.
 
Each book is given a title by the artist/writer and the cover decorated by them. The Sketchbook Project mails you a sketchbook that is standard and plain. What you put in and on it is up to you. You can even glue things on to its pages.
 
Each book is unique, there are no copies of it other than the original. Nationally there are several such libraries, but all books are sent to Brooklyn and other libraries barrow from the collection. If you want copies made, you will have to do them yourself. The blank book is not free, they cost about $30 (which includes the book, shipping and handling and processing fees as each book is copyrighted).
 
All the information is here:
https://www.sketchbookproject.com