I get a spam popup ad when I open this link. After closing it, when I click one "annotation" to be able to read it, it opens in a sidebar and all the others disappear. Closing the sidebar doesn't make them reappear. Reloading the page does, but as soon as I click on one inane annotation, all the others disappear again.

All in all, a very frustrating experience.

I recommend just downloading the original PDF instead: http://www-formal.stanford.edu/jmc/recursive.pdf

Then, you know you have the paper, and can share it with other people in the future, without some fly-by-night startup injecting spam popups or going under and invalidating the URL.