Translation:Do you have any books about his theories?
Actually I have found out that "nogen" is correct in this sentence, as it is a question.
"har du nogen æbler til mig".
As a native danish speaker, I would actually not say it like that. It might just be dialect and such, but to me it sounds wrong. ¨ However if you were to say something like "Are there anyone here who can read?" you could use both 'nogle' and 'nogen' ("Er der nogle/nogen her, der kan læse?")