You need to have multiple copies open at the same time if you want to refer to different parts at the same time.
Ctrl+f is great, but you end up losing the part of the book you were at before you started searching. So basically I needed to have 4 copies open at a time. 3 for different parts of the book I needed to refer to and one for searching. This made the actual size of the text way too small on a laptop screen.
Some of the problems could probably be solved with bookmarking software, but then you have to remember where each bookmark is instead of glancing at it.
I've managed to accommodate the need for multiple pages open at once by having multiple windows with multiple tabs.
This works much better for me than paper books due to freeing up desk space and not requiring multiple purchases of a paper text.
I use OS X though, so I have a convenient graphical window switching tool which shows me all the windows of a particular app, rather than a list of window names. Perhaps the experience is different for Windows and Linux users?
On the iPad, I make extensive use of notes, bookmarks and different coloured highlights. In some cases I'll use e.g.: yellow for definitions, blue for examples, pink for caveats. In other cases I'll use yellow for topic A, pink for topic B, etc. Thus the always-visible index of notes gives me twice as much information!
You can't easily get the same utility out of a paper book.
IIRC Firefox's built-in PDF viewer has decent integration with the browser back button, so you can search for text, read it, then press the back button on your mouse (or two-finger-swipe if you like making things complicated ;-)) to return to your previous page.
Not necessarily. I use the PDF-reader on OSX called Skim and it lets me bookmark the current page I'm on. Then I can just keep clicking the bookmark menu item and switching to the page I need. Only one copy. Each bookmark can have a label. Not too bad.
I also use Skim, it works really well. A pretty cool feature is the back and forward buttons, that hold your page if you skip through large chunks. For example, if I use the table of contents (Cmd + Shift + T) to go to the answers section, I can press back to get back to the question I was on. Then forward brings me to the answers once again.
That's basically my textbook workflow 90% of the time.
Potentially even more useful is the split view. Unfortunately, it only does horizontal splits, and only two at a time. I need to search again sometime for a reader with vertical splits, as horizontal splits are mostly useless on a little 11" screen.
Ctrl+f is great, but you end up losing the part of the book you were at before you started searching. So basically I needed to have 4 copies open at a time. 3 for different parts of the book I needed to refer to and one for searching. This made the actual size of the text way too small on a laptop screen.
Some of the problems could probably be solved with bookmarking software, but then you have to remember where each bookmark is instead of glancing at it.