1. Christmas Counts—Queens, New York;Audubon Field Notes,1965
2. The M 33C track radar (3-cm) as a tool to study height and density of bird migration;Blokpoel,1971
3. A preliminary study on height and density of nocturnal fall migration;Blokpoel,1971
4. Bird hazards to aircraft;Blokpoel,1976
5. Gull problems at Ontario airports: no magic solutions;Blokpoel,1980