A splendid, invaluable app for anyone who needs this kind of thing. (And, as I insist to my students, every high school, university, grad student, and instructor or researcher needs this kind of thing :-) )

More capable and reliable than its competition, and Jon's support is exemplary.

I've been using bibliographic database apps, of my own crafting or commercially-sold, for nearly 25 years. I've tried all of the competing apps for Mac OS -- Bookends is perhaps in need of a UI facelift and a few features could use some tweaking. But: I spend a good bit of my professional life in Bookends. I couldn't do my job without it.