From the entrance to the fence maze outside of Germantown Police HQ, head south for ten yards or so. You'll find a destroyed road. Follow that south to an intersection by two ruined houses. Then follow the road west for a little while and you will see a house. Look on the bookshelf.
To the northeast, halfway straight airline towards SatCom Array NW-05a: Down in the valley next to a few car wrecks. It's on the ground next to a skeleton and three ammunition boxes. Coordinates (1.4, 2.9) (Horizontal, Vertical Coordinates) according to Fallout 3 map. See map image attached below.
To the north, in a camp under a bridge. Watch out for a landmine at the opening of the camp that will blow book away and sometimes glitch into the wall disappearing.
Just west of the tower, towards Warrington Trainyard, in a completely destroyed house on top of a shelf. This is just northeast of the mostly intact house.