You need to complete all notebooks with any difficulty, but i suggest to enter with "boi" difficulty, find black key and knife, and save them in belt. Then enter with "default" difficulty and complete Albert, then You see what happens. And this will be easiest way to complete math.
Thank you so much! I was going to try to complete braniac difficulty and see if they would appear after I got 8 notebooks or something. I thought this because Strobovski goes silent on book 3 and I thought they would appear later rather than being the same the whole way or something. I owe you one!
