The one thing I really need from one of these task management platforms but that I can’t find is a way to manage, share, and track the reading of academic paper

The one thing I really need from one of these task management platforms but that I can’t find is a way to manage, share, and track the reading of academic papers and white papers on the site and on iPad (IMO iPad in the morning is the best way to consume papers.) That means being able to store and manage PDF files and snapshots of websites and add them to a reading list with tags for different users. And then in the reader interface to be able to take and share notes. Any suggestions would be appreciated. We tried Trello and Zotero but they sucked.