I don't know about the T68, but on the M96 the best I've found is AlReader (
https://play.google.com/store/apps/d...rland.alreader). It's actually designed, in part, for eInk displays, and it correctly handles screen refreshes, hardware buttons, and so on. It's completely navigable on the M96 using hardware buttons alone. Important for me, it also saves citations in a text-based format, and can sync and export easily to Dropbox, so I don't lose those citations in case something happens with the app or my device.