Alphabetical List their locations and where to find them
The Magas Codex Page 1
Londinium Bureau - Lunden - England
Go to the Londinium Bureau Office location on the map.
You will see high branches in a circle that you can't penetrate.
Climb high up and take a dive from a branch above the map marker to dive into the Londinium Bureau.
Here, you can dive underwater to get behind the locked office.
From the hanging platform you can shoot the oil jar to get inside the office.
The Magas Codex Page 4
Ratae Bureau - Ledecestre - England
Go to the Armour spot on the map. There is a big Assassin's sign on the ruins' floor.
There, look around for a big hanging bag that you can shoot down.
Do so and it will open a passage down.
Follow the slide-through gaps in the walls to get into the Hidden One's Office, where this item is.
Pick up The Magas Codex Page 4 in the back room of the Office.