Context

I am using Mathematica to create live documents - documents that are both interactive and show mathematical derivations. Now, I'm aware that there are certain symbols that are available via:

\[CapitalSigma]

or escSesc

However, some of the symbols I want (\in: $\in$, \subsetneq: $\subsetneq$) do not belong in the greek letters. Is there a list of something similar to this but lists Mathematica symbols instead of $\LaTeX$ symbols?

Thanks!