I compile most of my sketchbooks and research together in the form of collage.
I personally do not like to draw something into a sketchbook and that be it, it's stuck there for good.
 Therefore when I do draw into my sketchbook I take photocopy's of the drawing or the sketch for later use.
 I then cut them out along with imagery that I got inspiration from, artists I thought were relevant, etc.
and make a small A3 collage and stick that down into my book.
I like to think of my sketchbooks more as scrapbooks.