1. “Class E-a new class of high-efficiency tuned single-ended switching power amplifiers,”;Sokal;IEEE Journal of Solid-State Circuits,1975
2. N. O. Sokal A. D. Sokal “High efficiency tuned switching power amplifier,” 1975
3. “High efficiency RF power amplifier,”;Ebert;Bulletin of the Polish Academy of Sciences, Series Science Technical,1977
4. “Class E can boost the efficiency,”;Sokal;Electronic Design,1977
5. “Idealized operation of the Class E tuned power amplifier,”;Raab;IEEE Transactions on Circuits and Systems,1977