INFLUENCE OF BERNSTEIN MODES ON THE EFFICIENCY OF ELECTRON CYCLOTRON RESONANCE X-RAY SOURCE ArticleAndreev V.V., Nikitin G.V., Savanovich V.Yu., Umnov A.M., Elizarov L.I., Serebrennikov K.S., Vostrikova E.A.Review of Scientific Instruments. Том 77. 2006.