V. Veselago,“The electrodynamics of substrates with simultaneously negative values of ε and μ,”Soviet Physics Uspekhil, vol. 10, no.4, pp.509-514,1968.
C. Caloz, T. Itoh,“Application of the transmission line theory on left-handed(LH) materials to the realization of a microstrip LH transmission line,”Proc.IEEE AP-S USNC/URSI Meeting, vol. 2 ,pp. 412-415, June 2002