1. Wilton, J. R. 1915 Phil. Mag. 29 (6), 688–700.
2. Hogan, S. J. 1979b Ph.D. dissertation,University of Cambridge.
3. Chen, B. & Saffman, P. G. 1979 Stud. Appl. Math. 60,183–210.
4. Nayfeh, A. H. 1970 J. Fluid Mech. 40,671–684.
5. Hogan, S. J. 1980b Report, California Institute of Technology.