As an engineering student, I often find myself shuffling through old notes to find a quick summary of a topic or a concept that I use in other problems. This becomes quite tedious, as I tend to copy-paste what I wrote into the new notebook where I reference this note. I think that it would be nice to work in a virtual window that shows a cutout of the older notebook which has the notes that are relevant written down, and i can resize said window to fit in the newer notebook. As far as I understand, this would also help improve the reduction of size of the notebook, further enabling me to keep more notes on my iPad with the saved space. Imagine it as a hyperreference in a PDF document, where you reference back to what is already inserted to the file and you call back to it (quite similar to pointers in C/C++).