APA

Okruszko H., . (1990). Wetlands of the Biebrza Valley their value and future management. Warszawa: Polish Academy of Sciences.

Chicago

Okruszko Henryk, . 1990. Wetlands of the Biebrza Valley their value and future management. Warszawa: Polish Academy of Sciences.

Harvard

Okruszko H., . (1990). Wetlands of the Biebrza Valley their value and future management. Warszawa: Polish Academy of Sciences.

MLA

Okruszko Henryk, . Wetlands of the Biebrza Valley their value and future management. Warszawa: Polish Academy of Sciences. 1990.