We need an alternative to double-tapping to get the app navigation to appear.
Even with an opening page showing the user instructions in each issue, there are still questions of how to return to the main library.
Also in cases where there are many links on a page, it can be tough for the user to find a 'blank area' to double tap.
Maybe at the top of any page, if you pull down, you get a few nav options. Or a single-tap brings up a nav overlay.