1. D. E. Bently, Forced Subrotative Speed Dynamic Action of Rotating Machinery, ASME Publication 74-Pet-16, Petroleum Mechanical Engineering Conference, Dallas, TX, (1974).
2. A. H. Nayfeh, Nonlinear Oscillation, Wiley-Interscience Publication (1979).
3. D. W. Childs, Rub-Induced Parametric Excitation in Rotors, The University of Louisville, Kentucky, Report (1980).
4. D. W. Childs, Fractional-Frequency Rotor Motion Due to Nonsymmetric Clearance Effects, ASME Publications 81-GT-145, International Gas Turbine Conference and Products Show, Huston, Texas, March (1981).
5. F. F. Ehrich and J. J. O’Connor, Stator Whirl with Rotors in Bearing Clearance, ASME WA/MD-8, Paper 66 (1966).