Progress report on operation bird track 1964 through 1969.
Blokpoel, H. 1971. Progress report on operation bird track 1964 through 1969. National Research Council Associate Committee on Bird Hazards to Aircraft Fieldnote 59. November 1971. 30 pages.
Blokpoel, H. 1971. Progress report on operation bird track 1964 through 1969. National Research Council Associate Committee on Bird Hazards to Aircraft Fieldnote 59. November 1971. 30 pages.
