Leopoldo, G. D., & Capangpangan, M. B. (2007). Supercritical fluid extraction and chromatographic analysis of polynuclear aromatic hydrocarbons in Iligan City and Cagayan de Oro City street dusts: A method development and application study. The Mindanao Forum: official journal of the MSU-Iligan Institute of Technology.

Leopoldo, Girlie D., and Mario B. Capangpangan. "Supercritical Fluid Extraction and Chromatographic Analysis of Polynuclear Aromatic Hydrocarbons in Iligan City and Cagayan De Oro City Street Dusts: A Method Development and Application Study." The Mindanao Forum: Official Journal of the MSU-Iligan Institute of Technology 2007.

Leopoldo, Girlie D., and Mario B. Capangpangan. "Supercritical Fluid Extraction and Chromatographic Analysis of Polynuclear Aromatic Hydrocarbons in Iligan City and Cagayan De Oro City Street Dusts: A Method Development and Application Study." The Mindanao Forum: Official Journal of the MSU-Iligan Institute of Technology, 2007.