A perfect single source app for mind mapping documents. Well worth the try. Too bad this app doesnt show well with keyword searches. Hope more people find this app. Some PDF issues appear to be an uploading issue; that may be solved by a progress bar. Developer has good feedback and update priority. Looking to upgrade after some more testing (50 item limit per notebook). Great solution amongst many mind map/flash card/note taking apps out there that are too cumbersome (because you need to have multiple apps and physical books etc. [this is simple; one thing in front of you])