SOVON (1986) Cooperating Organizations Bird Research Netherlands. BSP experiences in four quarters blocks. LIMOSA 59 (1): 44-44.

Method In the breeding season of 1985 in the four fourth blocks of Atlas Block 41-25 (Achterhoek) the BSP performed, insight was obtained into method and time for this project. the method was broadly in line with what has is indicated under What does the counter?.

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