1. BRATMAN , V. L.,GINZBURG , N. S.,NUSINOVICH , G. S.,PETELIN , M. I., andYULPATOV , V. K.,1979 a,High Frequency Relativistic Eleclronics, edited byA. V. Gaponov-Grekhov(Gorky : Applied Physics Institute), p.157.
2. Common properties of free electron lasers