Reference

Mordecai G, Tyler PA, Masson DG & Huvenne VAI (2011). Litter in submarine canyons off the west coast of Portugal. Deep Sea Research Part II: Topical Studies in Oceanography 58(23–24):2489–2496.
Pham CK, Ramirez-Llodra E, Alt CHS, Amaro T, Bergmann M, Canals M et al. (2014). Marine litter distribution and density in European seas, from the shelves to deep basins. PLOS ONE 9(4):e95839.