Ferreira, A. and Vale, C. 2001. Seasonal and inter-annual variations of PCB and DDT contents in the oyster Crassostrea angulata from the Sado Estuary (Portugal). Ciencias Marinas. 27, 2 (Mar. 2001), 255–268. DOI:https://doi.org/10.7773/cm.v27i2.459.