Zhang, B., H. Zhang, and L. Wei. “Ag2S/WO3 Composites With Full Spectrum Photocatalytic Activity”. American Scientific Research Journal for Engineering, Technology, and Sciences, vol. 56, no. 1, June 2019, pp. 152-6, https://www.asrjetsjournal.org/index.php/American_Scientific_Journal/article/view/4714.