Putting a footnote in a section heading, as in:
\section{Full sets\protect\footnote{This material due to ...}}
causes the footnote to appear at the bottom of the page where the section starts, as usual, but also at the bottom of the table of contents, where it is not likely to be desired. The simplest way to have it not appear on the table of contents is to use the optional argument to \section
\section[Please]{Please\footnote{%
Don't footnote in chapter and section headers!}}
No \protect is needed in front of \footnote here because what gets moved to the table of contents is the optional argument.
© 2007–2018 Karl Berry
Public Domain Software
http://latexref.xyz/Footnotes-in-section-headings.html