1. Leppington, F. G. 1972 J. Fluid Mech. 56,101.
2. Ayad, A. M. & Leppington, F. G. 1977 J. Fluid Mech. 80,593.
3. Leppington, F. G. 1973a J. Fluid Mech. 59,129.
4. Van Dyke, M. 1964 Perturbation Methods in Fluid Mechanics .Academic Press.
5. Shen, M. C. 1965 New York Univ., Courant Inst. Math. Sci. Rep. IMM 342.