L. Martínez Pérez, V. Altuzar, N. Muñoz Aguirre, V. Gariba, -Febles., M. Lozada-Cassou, M. Aguilar-Frutis, O. Zela, and a-Angel., Application of the total internal reflection phenomenon as a gas sensing technique using evaporated SnO$_{2}$ thin films, Rev. Mex. Fís. 50, (2004).