ANALYSIS AND APPROXIMATE SOLUTIONS OF THE DISPERSION EQUATION OF SURFACE ELECTROMAGNETIC WAVES IN INSULATOR-METAL-INSULATOR STRUCTURES Article Kassandrov V.V., Nikitin A.K., Sumita B., Tishchenko A.A. Physics, chemistry and mechanics of surfaces. Publ by Gordon & Breach Science Publ Inc, Newark, NJ, United States. Vol. 8. 1993. P. 731-740