I'm trying to sort a very long bibliography alphabetically. Each entry is
its own paragraph, the first letter of each paragraph is the first letter of
the author's last name. The document is several pages long.

When I sort, each page is beginning again with A, in effect treating each
page as a separate, one-page list rather than a single, multi-page list.

It's as if there were section breaks in the file, but there aren't any.