The Note to Derek is a scrap in a drawer behind the register of the first shop on the left in the subway room full of clickers. It holds the combination for a safe close by.
A shop worker tells a coworker that Derek from the bookstore is letting them use his safe, and asks them to lock the writer's things in it at closing. Despite the title, the note reads as if it was meant for someone other than Derek.
Sneaking through this room is risky with the clickers around, so move slowly and use the counters for cover while you search the drawer.
Firefly Map
The Firefly Map is a note on a dead Firefly in the subway station downtown, on the stairs between the two escalators. It is the body to the right of the one carrying a Molotov cocktail.
Davidson's Firefly Pendant
Davidson's Firefly pendant lies underwater in a stone rotunda in The Capitol Building section of The Outskirts. It belonged to Melinda Davidson and is easy to swim past.
Evacuation Leaflet
The Evacuation Leaflet is an old FEDRA warning on the right-hand pavement in downtown Boston. Once you climb the collapsed street and Tess and Ellie start talking about the bombing, look by the base of a traffic light a car has hit.
Field Ops Log
The Field Ops Log is a soldier's patrol record inside the Goldstone Building, the tilted skyscraper downtown. Climb the stairwell toward the fifth floor; it lies beside the second dead soldier, along with a couple of 9mm rounds.