http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Some calculations for air resonance of a helicopter with non-articulated rotor blades
Aeronautical Research Council (Great Britain)
"Replaces R.A.E. Technical Report 72083--A.R.C. 34 332" -- page 1.
Includes bibliographical references (page 15).
Reports and memoranda (Aeronautical Research Council (Great Britain)) ; no. 3743