Stray: How to Find All 4 Notebooks in Chapter 4

gamerant.com:

Not long after entering the slums for the first time, Stray players will come face to face with the area's red-cloaked protector, Guardian. If they show him or any of the other robots the postcard from the outside that they picked up a little earlier, he'll mention a group of robots called the Outsiders and recommend talking to a robot called Momo in order to find out more about the outside world.

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Momo lives in a tall building near an orange neon sign, which is where players will need to head next if they wish to progress the main story of Stray. After reaching Momo, he'll reveal that his friends are now missing and that he's unable to contact them due to the transceiver that he's working on being faulty. To help him fix it, players will need to track down four notebooks that are scattered throughout the slums.

Momo will give players his notebook after they speak with him, before going on to reveal that he's now done with dreams of the outside world. After analyzing the notebook, Stray's robot companion character B-12 will suggest finding the other three notebooks, each of which is located in a tall building with the Outsiders logo (a white face with a circle for a mouth on a blue background) somewhere near by.

After getting Momo's Notebook, players should head back outside and look to their left. They should see a tall building with a large blue Outsiders sign on the roof and enclosed metal railings along the side. Upon reaching the roof players will need to disable the fan by removing the energy cell, which will allow them to drop down into the flat. There, beneath a box near the sofa, they'll be able to find Zbaltazar's Notebook​​​​​​.

Doc's Notebook can be found inside a locked safe in a flat