Latex sample rsfs

Using the "rsfs" Fonts in LaTeX

Ralph Smith's Formal Script is a script font that is more elaborate than the "calligraphic" font obtained by \mathcal. Like \mathcal, though, it includes capital letters only.

\documentclass{article}
\usepackage{mathrsfs}

\begin{document}
Let $\mathscr F$ be a sheaf.  Call it $\mathscr G$.
\end{document}

(Note that this is not to be taken as an example of good mathematical exposition.)