Dr. De Lang's Secret Notes

(When I opened the strange book again, I was able to find a small note hidden inside. This might be 4161031... should I take it?)

(After carefully removing the note, I closed the book. Once closed, it looked just like any other book.)

(I left the note in the book and closed it.)

Did you... wind up finding any additional information on 2111002? Where he disappeared, why he disappeared... were you able to find any one of that? Ah... that book... that must be 4161031. Mind if I look through it?