Disappearance of Self-Focusing for Few-Cycle THz Pulses S.A. Kozlov, A.A. Drozdov, M.A. Kniazev, D.A. Kislin, S. Choudhary and R.W. Boyd EPJ Web Conf., 195 (2018) 07002 Published online: 23 November 2018 DOI: 10.1051/epjconf/201819507002