Rangel-Rojo, R., A. Kar, B. Wherrett, M. Carroll, G. Cross, ., and D. Bloor. “Third-Order Optical Nonlinearities of a Polymeric Film Doped With a Novel Zwitterion, DEMI-3CNQ”. Revista Mexicana De Física, vol. 41, no. 6, Jan. 1994, pp. 832-40, https://rmf.smf.mx/ojs/index.php/rmf/article/view/2537.