Amplification of terahertz radiation in carbon nanotubesSulemana S. Abukari, Kofi W. Adu, Samuel Y. Mensah, Natalia G. Mensah, Kwadwo A. Dompreh, Anthony Twum and Musah RabiuEur. Phys. J. B, 86 4 (2013) 182DOI: https://doi.org/10.1140/epjb/e2013-30771-6