This is fantastic. Great work. Random question: Is there an app/software you used to do these doodles? I'd love to do something similar but I'm not as artistically gifted. Thanks!
As Gregory mentioned, he used Paper for part of these. If you are interested in trying it out, I recommend this video put together by Brad Ovenell-Carter - he does a great job of giving tips even if you aren't artistic: http://www.ovenell-carter.com/uncategorized/sketchnote-prime...
I'd recommend checking out Paper by 53; it's hard to not make something beautiful using it.