Here is a quick copy-paste from the Wiki.
* Vault 92; Found in the Living Quarters. It is in the bathroom of the men's quarters. Inside the closed bathroom stall. On the ground next to the toilet. * Arlington Library; Found in the children's section of the library. Past the Firehose Box. Go right. Past the Nuka Cola Machine. In the first room you see enter. In the right cubicle by a music stand on the floor. * The National Archives; Found in the first room in the Archive Sub-Basement, when not entering from the lift with Sydney. The Room is full of books and broken metal shelves, Music paper is on the bottom shelf of the west wall. * Springvale School; Enter the front door of Sprinvale Elementary and turn to your right. You'll enter a hallway. Go to the first room (Should be right in front of you) and there will be a couple of mattresses and a flipped over desk. Walk around over to the desk and right behind it is a sheet music book. * The Statesman Hotel; Found on the roof, near the music stands and chairs. * Roosevelt Academy; Found in the Arts and Athletics hall on the stage near the music stands.