We often get asked whether a PDF can be "converted" into a Book Creator book (particularly when a book has been created in Book Creator, exported as a PDF and then the original has been deleted!).
I'm sorry, you can't convert PDFs back into Book Creator books.
You could try copying and pasting text, but as we explain in a different article, Book Creator books are fixed layout so importing text can be problematic.
Perhaps the next best thing is to embed the PDF inside the book? When you click on the PDF, it will open inside Book Creator so you can read it whilst staying in the book.
There are numerous ways to do this, depending on which device you're using. The simple way is to import a file into Book Creator.
From the + button, go to Media > Import > File and choose, for example, a PDF. This will embed the document onto your page like below. In Read Mode, you can click on this document and it will open up the PDF.
In Book Creator for iPad, the process for embedding documents is slightly different. Please read our article 'Share content to Book Creator for iPad from your cloud drives'.