Centralized Control Area: check on the photos (press E to see them in the inspection window) pinned to the boards (somewhere early in-game iirc, found somewhere the picture is in the room that has the button that unlocks the A1 lower entry door, though I don't really remember if that is true);
Desperate Weepers: the door with the heart (the code 1314 is featured in the recording found on A3 on a shelf obstructing one of the ways out; careful: weeper close encounter inside, so better either wait until you get the rifle, or have a brain smasher) - check on the photo there;
Nightmare Castle: a pumpkin monster toy found somewhere in the second half of the game (after the "shower boss" that is).