where did you find the first two?
EDIT:
You must be afk so I'll just type where to get all three.
The first one is to the right after you get the camera (obviously).
The second will be in "Jet Postal" Simple enough it looks like a post office.
Entrance To Jet Postal.
The third and last will be in "Fighting McDonagh's Tavern" this one is probably the one your having trouble with because it won't show up untill you go into room 5.
Entrance to Fighting McDonagh's Tavern
Any other questions just ask me, Bioshock is one of my favorite games