If you run into troubles with the pdf-book-creator:
don't panic !
There is a button on top of every page called “Add/Remove selection”. As soon as you click this button the first time,
you will see on top of every page a book icon and buttons to
'add a page' to selection (or remove if already added) and to
As soon as you click the
'show/modify book'-button you come to a special page where all so far selected pages are listed. You can remove single pages from your selection using the trash icon next to each page entry. Or you can download your selection as pdf.
Also you can completly clear your selction, removing the blue book icon from every page header.