As of summer 2019, Math Reviews was still based on a plain TeX production stream, so any purely LaTeX methods aren't going to work.
The amsfonts
documentation (texdoc amsfndoc
) contains instructions for accessing the cyrillic font.
Here are the details for loading the font:
\newfam\cyrfam
\font\tencyr=wncyr10 \font\sevencyr=wncyr7 \font\fivecyr=wncyr5
\def\cyr{\fam\cyrfam\tencyr\cyracc}
\textfont\cyrfam=\tencyr \scriptfont\cyrfam=\sevencyr \scriptscriptfont\cyrfam=\fivecyr
Then {\cyr Sh}
works, or this definition provides \Sha
:
\def\Sha{{\cyr Sh}}
It's not mode-specific, and can be used in either math or text, but for the sake of clarity in the source, it's best to specify math mode if it represents a math object.
\Sha
as an example. (texdoc amsfndoc
) (But if this fails, send a message to MR asking for instructions. They surely use this notation.)