Photon Sails -- See Solar sails Here are entered works about very large lightweight reflective surfaces on spacecraft for propulsion by pressure of sunlight.
Photorefractive Materials Congresses : Symposium C on Photorefractive Materials: Growth and Doping, Optical and Electrical Characterizations, Charge Transfer Processes and Space Charge Field Effects
Photos -- See Photographs Here are entered works that discuss photographs themselves as objects of special interest, including their classification, cataloging, copying, coloring, mounting, etc. --subdivision Photographs under subjects for works that consist of actual, i.e. not reproductions of, photographs
