My question is, if Halmos' book "Naive Set Theory" is still up-to-date concerning contemporary mathematics, that is, is it outdated or not?
I really love the books so far, and while it's clear the notation is outdated, so far nothing contradicts what we had in the lectures. My assistant in calculus warned me about the book not being the newest though, so I'm a little confused right now.
Can I safely continue reading it without learning anything wrong or should I look out for another book? If the latter is the case, can anyone of you give me a suggestion which book would be better suited?
Thanks in advance!