Particularly in the humanities, authors can have multiple classes of
footnotes, including having footnotes of footnotes. The package
bigfoot extends LaTeX’s default footnote mechanism in many
ways, including allow these two, as in this example.
\usepackage{bigfoot} % in preamble
\DeclareNewFootnote{Default}
\DeclareNewFootnote{from}[alph] % create class \footnotefrom{}
...
The third theorem is a partial converse of the
second.\footnotefrom{%
Noted in Wilson.\footnote{Second edition only.}}