@article{22161, recid = {180249}, title = {Helicopter acoustics : proceedings of an International Specialists Symposium sponsored by the American Helicopter Society, Washington, D.C.; the U.S. Army Research Office, Durham, North Carolina; and the Langley Research Center, Hampton, Virginia, and held at Langley Research Center, May 22-24, 1978.. International Specialists Symposium on Helicopter Acoustics}, publisher = {National Aeronautics and Space Administration, Scientific and Technical Information Office ;}, address = {[Washington] :}, number = {22161}, pages = {2 pts. :}, year = {1978}, url = {http://library.usi.edu/record/180249}, }