Message mode - how to hide headers

[Jakub Neumann]

Hi,
I'm new to gnus and I'm using it to read/write mail (v5.9.0).
I have some questions about sending/replying mail (or article).
When composing/replying mail the default major mode is message mode. How 
to hide some headers, for example very annoying: References
(gnus-visible-headers doesn't work in this case).
and
how to customize *gnus-article-copy* buffer while replying (hide almost 
all headers). Its mode is Fundamental so it presents an article in raw 
form. It would be nice to see in this buffer only the body message and 
two or three headers (subject, from etc.) in font-lock-mode.

Thanks a lot