Ferreira, AM, and C Vale. “Seasonal and Inter-Annual Variations of PCB and DDT Contents in the Oyster Crassostrea Angulata from the Sado Estuary (Portugal)”. Ciencias Marinas 27, no. 2 (March 6, 2001): 255–268. Accessed May 3, 2024. https://www.cienciasmarinas.com.mx/index.php/cmarinas/article/view/459.