When you click on an internal link in a PDF book, which navigates you to another page/section, then if you want to return to the previous view (that you were reading and highlighting in it) there is no way!

Finding it by browsing through the entire book or by selecting the section from a multilayered list of contents, sucks!
(You likely didn't even notice the current page number before clicking)

Yes, you should bookmark the page you left before clicking on the link, but now which page have you just added to the list? It's not distinctive in the bookmarks!

Thus, it is urgent to add a button at the upper right called "Go to previous view"

(Same as navigation buttons on older desktop versions)