1. An analysis of the structure of Space-Time;Penrose;Adams Prize Essay,1967
2. Twistor Algebra;Penrose;J. Math. Phys.,1967
3. Solutions of the Zero Rest-Mass Field Equations;Penrose;J. Math. Phys.,1969
4. Twistors and the Quantization of Curved Space-Time;Penrose;Intern. J. Theoret. Phys.,1968
5. Twistor Theory: An approach to the Quantization of Curved Space-Time;Penrose;Phys. Reports 6C No. 4,1973