The Survivors note is an optional artifact in the last house of the Pittsburgh suburbs. Climb to the second floor, enter the first bedroom on the left and check the computer desk.
The final Ish note. He writes from the suburbs with Susan and a few of the children beside him, still clinging to his faith in people.
A single door left open let a horde into the sewer camp. The survivors sealed the infected inside and wrote a warning on the outside. Ish had to hold Susan back from running in after her lost children. What happened to Ish afterward is never shown.
Antiparticles
Antiparticles, issue 11 of Savage Starlight, lies on the console in the bridge of the wrecked fishing boat on the beach at the start of The Suburbs.
Boat note
The Boat note is an optional artifact on the bridge of the beached fishing boat at the very start of The Suburbs. Climb onto the deck, step into the wheelhouse and grab it from the console beside the Antiparticles comic.
Bomb: Containment
Bomb: Containment is a training manual on a shelf in the sewers of The Suburbs. It makes nail bomb blasts 1.5 times wider.
Cornered note
The Cornered note is an optional artifact behind a door near the sewer ambush site in The Suburbs. After the runner and clicker attack, climb the stairs, go through the door on the left and find it on a bench by the bodies in the corner.