Question about Ebooks on ipad

Yeah, i downloaded a free ebook, then clicked 'open with' on the top of the screen, and there Pereira's app was selectable. Also, in itunes, one can manage the ebooks of this particular app.

Finally...!, i can download chesspub's files, all cb format and read them correctly with a board on the side.
Thanks for posting this request, and thanks to blundersgalore.

and thecombinator for his answer, great find.