``.
Note that these are reverse quote, or ``back-tick'' characters,
usually found on the upper-left hand side of PC-style keyboards
(however, the Sun Type 5 keyboard puts it in the upper right). The ''
character is made by typing ''. In Emacs, the default mode for
LATEX files (called tex-mode) will generate the proper
characters when you press the " key. LATEX mode is automatically
loaded when you load a file ending in .tex that has a
\documentclass command near the top.