VERSTRAEL T, FLINKS H, SZÉP T, PROP J, CAMPHUYSEN K, GRAVELAND J & BIJLSMA RG (1996) Dutch Ornithological Union: National day 1994: Eutrophication and waterfowl in the Dollard. LIMOSA 69 (1): 29-29.

Eutrophication and waterfowl in the Dollard Dutch Ornithological Union: National day 1994: SOVON VBN

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