1. Ueher die Ausbreitung der Wellenin der Drahtlosen Telegraphie;Sommerfeld;Ann. Phys. Lpz.,1909
2. Physical Reality of Space and Surface Waves in the Radiation Field of Radio Antennas.;Norton;Proc. Inst. Radio Engrs.,1937
3. The Propagation of Radio Waves Over the Surface of the Earth and in the Upper Atmosphere II.;Norton;Proc. Inst. Radio Engrs.,1937
4. The Bending of Electric Waves Round a Conducting Obstacle.;Macdonald;Proc. Roy. Soc.,1903