Hi, I'm looking for a good solution to manage a PDF collection on an iPad using tags. My needs are as follows: - Using multiple tags to search for PDFs: Most applications using tags that I've tried doesn't allow to use more than one tag for search. However I'm using a multi axial classification for organizing the PDF and I need to be able to search them with multiple tags. In fact I'm looking for a Yep equivalent for iPad. - Reading PDF and basic annotating (highlighting + notes), but it could be done in another app if needed. - Syncing, could be dropbox, gdrive, webDAV, iCloud (one can dream). Until now, I have tested Goodreader, PDF Expert, iAnnotate, Documents. I really like their functionalities for reading and annotating, especially PDF Expert, but I can't search using multiple tags. On the other hand, I have looked into reference manager, such as Sente, but they are conceptually a bit more complicated (references vs PDF) and I am still not satisfied by the search options. I haven't yet tried Papers 3.0, because I have the previous version and I heard a lot of bad reviews about the new version. iPad apps are not very expensive, but at the end at the day I spend > 60 $ and I still haven't found a satisfying solution, so any help would be greatly appreciated.