1. Gibson, J. E., Nonlinear Auiomatic Control, McGraw-Hill Book Company, New York, 1963, pp.380-385.
2. Gelb, A., and Vander Velde, W. E., Muliiple-Input Describing Functions and Nonlinear Design, McGraw-Hill, New York, 1968,pp.163-185.
3. Attitude stabilization of flexible spacecraft during stationkeeping maneuvers