TY  - RPRT
TI  - Counter-rotating propeller noise directivity and trends
AU  - Block, P. J. W.
AU  - Klatte, R. J.
AU  - Druez, P. M.
PY  - 1986
UR  - https://ntrs.nasa.gov/citations/19860060680
ID  - 19860060680
ER  -