Abdullah, A. M., et al. “Synthesis and Characterization of Vanadium Substituted Potassium Tungsten Bronzes, K<sub>x< sub>V<sub>y< sub>W<sub>1-y< sub>O<sub>3< Sub>”;. Journal of Scientific Research, vol. 4, no. 2, Apr. 2012, p. 507, doi:10.3329/jsr.v4i2.9349.