Silva, A. A. R. da, I. Lobo, C. L. B. Guedes, and J. P. Pinto. “Analysis of Polycyclic Aromatic Hydrocarbons (PAHs) in Soils Using Ultrasonic Agitation, heater/Mini Condenser Tube and Gaseous Chromatography”. Semina: Ciências Exatas E Tecnológicas, vol. 27, no. 2, Dec. 2006, pp. 105-12, doi:10.5433/1679-0375.2006v27n2p105.