[OoC: @Betimi you cannot take 20 on knowledge checks. Reasons? First, knowledge skill says it takes no action. You either know the answer or you don't. Second, knowledge skills do not let you retry (see first reason). Which is what taking 20 is all about. You keep retrying until you succeed. Also, at what point would you realize you have the right answer? Taking 20 on open locks would eventually allow you to unlock the lock. Success! Does a light bulb appear above your head when you finally have the correct answer? 
However, if you had access to a well stocked library then I might consider a player to take 20 for knowledge checks.]
However, if you had access to a well stocked library then I might consider a player to take 20 for knowledge checks.]
