I read in a book when u have AK go ahead and push.
Normally no, this is not the case. I highly advice against open pushing with AK lol.
There is no concrete answer when/how to play a certain hand, there are times when it is better to play a hand a certain way - but they are simply guidelines.
Take into account your POSITION (most important), Blind size/stack size if its cashgame, the player(s) you are up against (Their betting pattern/agressiveness).
If it seems appropriate to push given these conditions, then by all means push with AK. If its 15/30 blinds with a stack of 2000 chips into a tight player, why oh why would you ever push AK?
I was at a $200nl cakepoker table, where a guy would open push his whole stack AIPF if he had AA/KK/AK. Dont do this.