Subjects
- Mining.1
- Money.1
- Mountain railroads.1
- Naval yards & naval stations.1
- Ocean liners.1
- Offices.1
- Ordnance industry.1
- Panamanians.1
- Paper industry.1
- People associated with manual labor.1
- Petroleum industry--United States.1
- Petroluem industry.1
- Photographic interpretation (Military science)1
- Piers & wharves.1
- Postal service.1
- Pottery.1
- Power plants.1
- Prints shelf.1
- Pumping stations.1
- Pumps.1