[AUCTeX] Defining new entry types in bibtex mode

[Sven Bretfeld]

Hello list

Can anybody give me a hint? I want to define some new entry types, so
that I can create templates by hitting a key combination in bibtex
mode similar to hitting C-c C-e b for a book.

For example, by hitting C-c C-e C-r

@customa{,
 author = {},
 sortkey = {},
...
}

should appear. I cannot find an explanation in the AucTex manual.

Thanks for help.

Greetings,
Sven