V. V. D. Berk

The White-breasted Kingfisher, Halcyon smyrnensis, in Turkey: On the occurrence of an endangered species

M. Kasparek, V. V. D. Berk, 1988 .

Action plan for the White-headed Duck (Oxyura leucocephala) in Europe. Technical Report, WWT

J. Holmes, H. Opitz, H. Garrido, 1996 .