About the wording of Fermat`s principle for light propagation in media   with negative refraction index
  In this work is elaborated the wording of Fermat`s principle for electromagnetic waves spreading in materials with negative index of refractions (MNR). The recent experiments with such material has confirmed their main characteristics, predicted earlier. It is shown that for MNR not applicable wording of Fermat`s principle through minimum (or extremum) of time of spreading the wave between two points. The correct wording for this case is a wording through extremum of total optical length for way between two points moreover optical length at passing of wave through MNR is taken negative. In paper are considered some properties of original flat lenses, executed from MNR. 
V.G. Veselago