ELISP (was: Agenda views w/m: inconsistency, bug)

[Karl Voit <devnull@Karl-Voit.at>]

* Carsten Dominik <carsten.dominik@gmail.com> wrote:
>
> You are looking for a view that covers 30 days.
> The view you are requesting can be made with
>
> C-u 30 C-c a a
>
> or with a simple custom command that sets
> org-agenda-span to 30 in the options section
> of the command.

I am (almost) to afraid to ask here (OT, newbee, ...):

For now I used:

,----[ from my .emacs ]
| (defun vk-export-agenda()
|   "Exports monthly Org-mode agenda to agenda.ics file"
|   (interactive)
|   (org-agenda-list)
|   (org-agenda-month-view)
|   (org-write-agenda "~/org-mode/agenda.ics")
| )
`----

I tried by myself but failed miserable. How can I add this
org-agenda-span to this function definition?

And: is there an (E)LISP book/URL you can recommend? I do have
programming experience and I noticed that I should learn ELISP in
order to get most of my editor ...

Thanks again in advance!

-- 
Karl Voit