The Notebook is one of the missing items that you need to recover and return to the correct time period. This Notebook must be returned in the time of Da Vinci’s Workshop (1516 AD 4 o’clock in your Time Device). To return it, give it to the bearded man.
How to Get the Notebook
Go to Statue of Liberty (1882 AD 10 0′ clock on the time device), its tricky to get it, you have to jump to the highest point of the legde then go to the left and jump off and hopefully land on a building where the notebook will be.