[texhax] how to use lettergothic?

[Karl Berry]

    So could you please explain what
    the correct algorithm is?

The name used with \font must match (exactly) the .tfm filename.  That
is the only reliable algorithm.  It is fruitless to try to deduce such
names.

Exception: unless you are using XeTeX or (one day) LuaTeX, in which case
you can use system fonts by their system names.

Hope this helps,
karl