Write an iPad app with Cordova (Intel XDK) with a 5 voices menu.
First 4 voices just open an HTML page. The last one open a gallery with 20 PDF preview that scroll horizzontally with swipe.
When a PDF thunbnail is pressed The corrisponding PDF is opened (two pages in landscape mode, one page if portrair).
Once The PDF is opened The user can swipe, pinch to zoom. Tapping on The page a menu with pages thunbnail
All The artwork will be provided.