There are 22 lore items to collect in total and they all must be collected in a single run. Some areas will become blocked off as the story progresses, so I suggest to grab the notes as you go.
1) George - When you reach the Mood Booth a fight will begin. In the opposite direction of the bobbies is a house with an open window. In there, on the kitchen table, is this note.
2) Party Supplies - Upon seeing Victoria's mother for the first time, head down the stairs and you will see a bunch of dead people and party supplies. On the counter near the stove is this note.
3) Upside for Downers - After entering the sewers, look ahead and you will see two men, both with their head in their hands. To their left on the ground, crumpled up, is this note.
4) A Bridge Too Far - A cut-scene featuring Victoria's father will play. Once you have control and are at the military base, look left. Up the stairs and on a table near a machine which says "QUARANTINE STATUS", you will find this note.
5) Safety Last - On the planks, immediately after they shake and Victoria stumbles slightly, there is a jump. On the wall straight ahead following the jump is this note.
6) Worker's Note - As you are walking along the planks, keep an eye out for a blue sign with a table to its right. On that table is this note.
7) No Requests - Eventually you will climb some stairs and be confronted with a tv and its searchlight. On a support pillar to the right of the light is this note.
8) Beautification - When you enter the quarantine area (indicated by big yellow writing at the top of an archway), there will be two people crouched over with particles around them. Look to your right and you will see a barrel. On a door very close to the barrel is this note.
9) Health Pamphlet - Next to the door is an alley way. Go down it until you reach the rope then whip yourself up and climb onto the high ledge next to you. Jump down and look behind you and you will find this note.
10) Operator Manual - In the room where you disable the downer detector (follow the cable from the downer detector to a window up high), it is on a table on the right.
11) Bad Batches - In Haworth Labs, enter the vent in the shower room and move ahead. You'll be greeted by a room with three people and a lot of steam venting, as well as a wheel. Deal with the people, use the wheel to stop the steam (which hurts you) and enter the vent to the left of the wheel. Turn right then immediately left where a red light is. Follow the vent along until you're in a room. On a cart in this room is the note.
12) Applied Phrenology - You'll be tasked with restoring the power; this is done by activating two switches. Next to the higher switch (left of where you entered the factory) is this note. Hard to miss.
13) Worker's Manifesto - Once you have both switches activated, go back outside the room where you activated the first switch (it is the lower of the two, not far from Verloc's door). On its left is another door and a red button that will now work. Press the button, enter the room and on a table at the back left of the room is this note.
14) Untidy - In the night section, there will be another downer detector with a cable that leads up to an open window. Get in this window (go past the tv searchlight and climb/whip then jump across). Once inside, the note is crumpled up in a tray, on a table to your right.
15) Peace Offering - When you encounter the man in a leather jacket (with various other people around him) turn around and look near the alleyway stash door for some rope. Whip yourself up and walk across the plank. Jump forward then turn left, you should see some purple lights. Jump to the purple lights and fall down the hole in the roof. On a table in this room is the note.
16) Spanked - Just past the previous note, you will enter a hole in the fence and see three bobbies ahead. Follow the cable to the left, into a small shed. There is a man in here and a switch. Crumpled up on a red table, to the left of the switch, is this note.
17) Permanent Solution - Very soon after entering the Old Bailey District, you get an objective to retrieve a dart gun. Directly beneath the dart gun is this note.
18) Highly Classified - Destroy the Joy Pill Allocator then take the elevator and go through the vent. Jump across to the other ledge using the whip and look for an open window. In this room on a set of drawers is the note.
19) Unfiltered - In the Waterworks facility, once you exit the vent go left. Keep going until you see a big circle aquarium. On a desk a few steps past this is the note. Additionally, on the wall above it says "Filtration, Engineering and Adulteration" with arrows.
20) Burning Bright - In the prison, you will be tasked with gathering your equipment. When you happen upon the room with the safe containing your gear, look on the shelves. It's on the lowest shelf sort of opposite the safe.
21) FAQ - Climb through the window into Victoria's house (you'll be in a bedroom) and look for a closed door. Open it and climb the stairs. The note is sitting on the toilet in her bathroom.
22) Johnny Bolton's Plans - As part of the main story, you will be required to obtain these plans from Johnny's safe house. They are on a table to the right as you enter.